Up is dry goods, "three acids and two bases" once all produced, the world will undergo major changes, the world after the war, who first restore these 5 kinds of mass production, who is one step ahead of the industry, triggering a global "big bang"!
There are many places in this article where electricity is needed, in order to avoid some people saying where will there be electricity after the war or after the end of the world?
I deliberately wrote another article [Survival: Strategic Material Reserves--- the principle and acquisition of [electricity]], normal industrial electricity production, the wild environment has been obtained, everyone slowly look.
First talk about the production idea of triacid and two bases, and then expand it
【Sulfuric acid】: Calcined pyrite + lead catalytic oxidation, or distillation of gallium alum or green alum, direct distillation can obtain concentrated sulfuric acid. (Pollution or something can not be more demanding)
【Hydrochloric acid】: sulfuric acid + sodium chloride
【Nitric acid】: sulfuric acid + saltpeter
【Sodium carbonate】: Dig directly from the salt lake.
【Potassium carbonate】: Burn grass and wood ash (same high pollution and high energy consumption)
【Calcium hydroxide】: Calcined limestone (smouldering firewood to get charcoal, charcoal burning temperature is enough to decompose limestone), add water to get calcium hydroxide.
【Sodium hydroxide/potassium】: Sodium carbonate/potassium + calcium hydroxide (caustic method)
【Ammonia】: Fecal urine + sulfuric acid distillation, sodium hydroxide in exchange for ammonia (Kjeldahl nitrogen method)
sulphuric acid
Vigorous miracle - early lead chamber sulfuric acid
Sulfuric acid is no stranger to everyone, and it can be said that it is the most famous of all inorganic acids. It is often possible to see cases of sulfuric acid disfigurement or accidental ingestion of sulfuric acid leading to esophageal resection in various life popularization programs. So that ordinary people without chemical knowledge know that sulfuric acid is highly corrosive and absolutely untouchable. In modern industry, sulfuric acid is one of the most important industrial raw materials, fertilizers, explosives, batteries and other aspects can not leave sulfuric acid.
Sulfuric acid was first discovered in the smelting process of ore, and humans tasted the sweetness after discovering that metals can be refined from ores. Gradually, a hobby evolved, that is, to find a mineral and burn it to see if it could refine something unexpected.
At this time, a refining process called dry distillation gradually appeared. The main reason for the emergence of the dry distillation process is that the ancients found that some ores produce gas during the heating process when refining ores. From a naïve point of view, they generally believe that these gases are the essence of the so-called ore, and naturally cannot be allowed to volatilize at will, so they developed a process of using closed containers and indirectly heating outside the container, while collecting these gases.
With the new process of dry distillation, we begin to refine ore, starting from that substance, of course, the more vivid the human habit, the better. As a result, sulfates, mainly copper sulfate and iron sulfate, began to enter people's field of vision.
Alum (ferrous sulfate) and cholestium (copper sulfate) crystals, both of which produce sulfuric acid after being distilled
When iron sulfate or copper sulfate is heated, the two minerals decompose to form corresponding metal oxides and sulfur trioxide, which continues to react with the crystalline water in the ore to produce sulfuric acid. In the Eastern Han Dynasty, there were alchemists in China who prepared sulfuric acid by dry distilling gallium alum. The European record of sulfuric acid appeared in the middle of the 13th century, corresponding to the era of Guo Jing and Yang Guo in the Archery Trilogy in China. Alchemists at that time used distilled alum to obtain sulfuric acid, so in ancient times, Westerners called sulfuric acid alum oil.
We said that dry distillation requires placing the ore in a closed container and then indirectly heating it outside the container, what material is used for this closed container? The first thing that can be determined is that this material needs to be corrosion resistant and at the same time has high temperature properties and can be used at high temperatures. It seems to be very demanding, but fortunately, in the early days of human evolution, we were lucky to find this material, that is, pottery. The early distillation of sulfuric acid was to put the ore in a clay pot and then heat it on a fire to introduce the vapor into a glass container filled with water (yes, you read that right, it was glass, which has been used by humans for more than three thousand years, and the glassmaking technology in Europe in the thirteenth century has been quite developed) to get a certain concentration of sulfuric acid.
One disadvantage of the method of using dry distillate sulfate to prepare sulfuric acid is that it requires a high reaction temperature, and the decomposition temperature of copper sulfate requires at least 650 °C. This limited the production of sulfuric acid, so people turned to another process for producing sulfuric acid. That is the use of sulfur combustion. Of course, the main product of sulfur combustion is sulfur dioxide, if you are lucky, there is a part of sulfur trioxide, these sulfur trioxide vapor can be combined with water vapor to form sulfuric acid, but the yield of sulfuric acid is very touching, sulfuric acid made of sulfur is called sulfur oil.
The time came to the beginning of the seventeenth century, when our country was in the Ming Dynasty, and the Donglin Party was fighting with a group of eunuchs. At this time, in Europe, the sulfuric acid industry led to a revolutionary advance, that is, the introduction of nitrogen oxides. It has been found that the addition of some saltpeter when burning sulfur can improve the yield of sulfuric acid. The mechanism of this reaction is that saltpeter produces nitrogen oxides in combustion, which can oxidize sulfur dioxide that appears during sulfur combustion, and finally form sulfur trioxide.
The earliest mass production of sulfuric acid is the British Wade, who uses about 100L of large glass bottles to produce sulfuric acid, the specific process is to first put a ceramic plate on the glass bottle with sulfur and saltpeter, and then put a little water in the bottle, and then ignite the sulfur, and then race the bottle up, after a period of time to get sulfuric acid.
The British Wade, who is also very interesting, is said to be a doctor, the reason for making sulfuric acid is to produce sodium sulfate from sulfuric acid, and then sell sodium sulfate as a health supplement. This person claims that sodium sulfate has a detoxifying effect and cures all diseases, if it is replaced by a role like Zhang Wuben today. So the British also charge an IQ tax.
This method is very simple and rude, first of all, the glass bottle is not resistant to pressure, not suitable for pressure vessels, so the volume of the glass bottle can not be too large. In addition, the reaction is the reaction of generating gas, so the amount of feeding in a single operation is impossible, otherwise a large amount of gas generated will directly make the glass bottle burst. Let's take a closer look at the raw materials added by this method, and then change it to black powder. It can be seen how hard the production of sulfuric acid was at that time, it is said that Wade's factory had more than 100 glass bottles, and then hired a large number of workers, day and night repeated the process of feeding, igniting, adding stoppers, and then pouring. The labor intensity of the workers is quite large and the safety of operation is difficult to guarantee, which is worthy of the sweatshop of the evil capitalism and the model of vigorous miracles.
It is worth mentioning that during the War of Resistance Against Japan, our Eighth Route Army also used a similar method to make sulfuric acid, but replaced the glass bottle with a large water tank commonly found in the countryside. Due to the lack of heavy weapons of the Eighth Route Army at that time, these sulfuric acids were mainly used to produce high explosives.
In view of the characteristics of glass bottles that are brittle and not resistant to pressure, people gradually began to consider the use of new materials as reaction vessels, and finally in the middle of the eighteenth century, that is, during our Qianlong years, the British Robck first considered the use of lead as a reactor material. The biggest disadvantage of lead as a reactive material is that the texture is very soft and does not provide strength. That's okay, we could consider using an impervious material as the overall frame and then solving this problem with lead plates as lining. In the mid-eighteenth century, the era of large-scale steelmaking had just begun, and the manufacture of steel was not yet mature. Therefore, the earliest lead chamber was made of wood as a frame.
Due to the low production intensity of the lead chamber, with the increase in the demand for sulfuric acid, people have to adopt the so-called vigorous miracle method, constantly making larger lead chambers, and constantly increasing the number of lead chambers to increase the production of sulfuric acid. In the early days, the volume of the lead chamber reached 8 cubic meters, and by the beginning of the nineteenth century, there were more than 300 lead chambers in a sulfuric acid plant in the United Kingdom, and the volume of each lead chamber was as high as 25 cubic meters, which is still a fairly large reaction equipment to this day. The French also went further and further down the road of violence, creating a lead chamber of 180 cubic meters and also challenging the lead chamber of 5,000 cubic meters, which of course collapsed directly during operation.
Lead chamber method sulfuric acid apparatus, can be seen mainly wooden frame lined with lead plate composition
In the nineteenth century, the rapid development of the European textile industry, the demand for sulfuric acid further soared, people gradually realized that relying on extensive increase in the volume of equipment, increasing the number of equipment is still unable to meet the demand. Therefore, a series of improved processes were born, and with the efforts of many researchers, the lead chamber sulfuric acid finally moved from indirect to continuous, and the process of which will be the main content below.
From intermittent to continuous
The early lead chamber method of sulfuric acid, this process is a typical intermittent process, we review the production method of this process: add sulfur and saltpeter in the lead chamber, add a little water, and then ignite the reaction to generate sulfuric acid, repeat this process continuously, and finally obtain a certain concentration of sulfuric acid. From this example, let's summarize the general law of the intermittent process. First of all, the intermittent process is generally divided according to the operation cycle, and a certain operation is carried out in one operation cycle, and then repeated in the next cycle. Secondly, the operation of each cycle is divided into the main operation process and the auxiliary operation process. Corresponding to the sulfuric acid production, the process of producing sulfuric acid in the lead chamber after ignition from sulfur and saltpeter is the main operation process, which is actually an "efficient" reaction process. The artificial addition of sulfur and saltpeter, ignition, including the transfer of sulfuric acid after the end of the reaction, which is an auxiliary operation process, is indispensable in production, but has nothing to do with the reaction. Finally, the biggest disadvantage of intermittent operation is that there are a large number of auxiliary operations in the operation cycle, which waste time, increase manual labor, equipment production capacity is still low, and the early lead chamber method is often hundreds of lead chambers but the output is very limited.
Essentially, the batch production process is an inefficient process, but it is such a process that is widely used in actual production until today. Therefore, an important task of modern engineering is to turn intermittent into continuous and increase the processing power of equipment. Due to the requirements for equipment capacity, lead chamber sulfuric acid is no exception to begin the process of intermittent to continuous conversion. This journey has lasted for 100 years, and now let's sort out this process.
First of all, we look back at this reaction, the actual process of the reaction is sulfur dioxide is reacted by nitrogen oxides, and the addition of sulfur and saltpeter, ignition these processes are nothing more than the provision of sulfur dioxide and nitrogen dioxide, as long as we can stably provide these two substances, we can achieve the continuity of this process. Naturally, we can think that if these two steps are carried out in two separate devices, one device continuously produces sulfur dioxide, and one equipment continuously performs sulfur dioxide oxidation, the whole process can be carried out continuously.
With the technical conditions at that time, the continuous occurrence of sulfur dioxide was really feasible, why? Because of the development of coal-fired heat engines, people have an understanding of continuous combustion equipment and operation, and related thermodynamic models have been established. It should be known that in the middle of the Qianlong Period, the British Watt had already invented a steam engine that could be used for actual production, and in the early eighteenth century, that is, during the Jiaqing period, the steam engine was able to stabilize the steam and push the train all over the street. In other words, humans were already making boilers at that time. Therefore, it is not difficult to stably burn sulfur dioxide, the production of nitrogen oxides is similar, as long as sulfur or pyrite is continuously added to the boiler, sulfur dioxide can be continuously generated, and the rest only need to hire a few boiler workers to get it done.
The advent of the steam engine is considered the beginning of the Industrial Revolution, at least in the chemical industry, due to advances in combustion technology, continuous gas generation became possible, and steam began to be supplied to chemical containers as a heat source.
The other is the improvement process of adding water, the early lead chamber method needs to add water to the lead chamber wall, which is very unfortunate to add water is really a problem. Suppose that the inspectors traveled back to the early eighteenth century and faced with the problem of adding water to the lead chamber, you shouted, "Commander of the Second Battalion, pull up our centrifugal feed pump." Hearing this, the second battalion commander looked embarrassed, and he sadly told you that it was more than 90 years before 380V alternating current was invented. You think about it, and indeed it is, and ask, "Then what else can drive the energy of machinery?" The second battalion commander said happily: "Of course, the steam engine was invented not long ago, and steam can be used as a driving force to push the piston to absorb water." "You hear this, what? Steam power? It wouldn't be more convenient for me to pass the steam directly into the reactor. Eventually, people of that era adopted the process of directly injecting steam into the reactor. As a result, the improved lead chamber method was invented.
When breakthroughs were made in the continuous occurrence of sulfur dioxide, people also had a better understanding of the reaction mechanism. In the early days, people simply found that adding saltpeter to sulfur can increase the yield of sulfuric acid, and the principle of it does not care so much, some people once thought that saltpeter produced oxygen during combustion to oxidize sulfur dioxide to sulfur trioxide. Until 1806, that is, during the Qianlong period, for the first time, chemists passed sulfur dioxide and nitrogen dioxide into the reaction bottle to produce white crystals, which could be used to produce sulfuric acid and release nitric oxide gas by passing this white crystal into the water. This process has attracted the attention of many chemists, and after a long period of research, it has been found that this white crystal is nitrososulfonic acid, and the entire chemical reaction process can be represented by the following cycle
The reaction mechanism of sulfuric acid by lead chamber method is generally considered to be the combustion of saltpeter to generate nitric oxide, and then oxidized into nitrogen dioxide in contact with air, carbon dioxide reacts with sulfur dioxide with water as an oxidant to form nitrosulfonic acid, and nitrososulfonic acid hydrolyzes to form sulfuric acid and nitrogen dioxide, nitric oxide.
This cycle is not particularly familiar, you can pay attention to the role of nitrogen oxides, you can be surprised to find that the reaction process is strictly oxygen as an oxidant, and nitrogen oxides after a cycle actually does not change. This is not very similar to what we call catalyst. Of course, at that time, chemists did not have this awareness, but felt that this reaction was very wonderful, and the real catalytic concept was proposed 30 years later, that is, 5 years before the opium war began.
Now, we have been able to continuously generate reaction raw materials, reactions can also be carried out continuously, the reaction mechanism has also made significant progress, at this time human beings began to move their minds again, since the previous nitrogen oxides in the reaction process is theoretically not consumed, then can we let nitrogen oxides in the reaction system continue to circulate.
The idea is very good, so let's start, first of all, we add an absorption tower behind the lead chamber to absorb the nitrogen oxides, this process was first proposed by the French guy Guy Lusack, so this tower is also called Guy Lusack Tower. This process is to present some correct thinking, but it is very unfortunate that the absorption of nitrogen oxides, especially nitric oxide, is not good. This reminds me of a recent exhaust gas treatment project, where nitric oxide is poorly soluble in water, so it must be oxidized to nitrogen dioxide using an oxidizer to absorb it, which has to cost a lot of chemical costs. This problem also exists in the lead chamber method, and even if the solubility of nitrogen dioxide in water is acceptable, the absorption effect in concentrated sulfuric acid is also very poor. Therefore, only the use of water or dilute sulfuric acid absorption can be considered, so that the absorption effect is good, but in order to reuse the nitrogen oxide after the absorption of water, this part of the absorbed water must be mixed into sulfuric acid, which reduces the sulfuric acid concentration, and it is not economical to concentrate it later. Therefore, this technology has not been adopted for a long time.
Guy Lussack, a famous French chemist with extraordinary achievements in chemistry, now France has an organization of seventeen top chemistry schools, named the Guy Lussack Group.
Even this is not difficult for human beings, and 9 years after The Death of Guy Lussack, a British plumber, Clover, proposed to add a tower between the furnace and the lead chamber, which is also known as the Clover Tower. The principle of The Clover Tower is that what comes out of the Guy Lusack Tower is dilute sulfuric acid and there are nitrogen oxides in it, and we make contact with the sulfur dioxide and nitrogen oxides generated by combustion in the Kolov tower, and in this process sulfur dioxide reacts to form a part of the sulfuric acid, which increases the concentration of the acid and makes it a product-level concentrated sulfuric acid. Nitrogen oxides, on the other hand, are released from contact with high-temperature combustion gases and enter the lead chamber along with unabsorbed sulfur dioxide.
The final molded lead chamber sulfuric acid process, vulcanization and saltpeter combustion generated by the mixture in the Kolov tower and the dilute sulfuric acid from the Guy Lusak Tower contact, a part of the reaction occurs to make the dilute sulfuric acid thickened, while the nitrogen oxides in it are steamed out, into the lead chamber reaction, the reaction gas is sent into the Guy Lusak Tower with dilute sulfuric acid absorption, and then sent to the Klofta.
In addition, there are a series of improvements to the lead chamber itself, first the packing tower technology began to appear, in fact, the Guy Lusack tower is a packing tower, which uses cinder as the filling. In order to enhance the gas-liquid contact effect, the lead chamber is no longer empty, and it is filled with ceramic filler. At the same time, due to the large-scale production of steel, we can replace the lead plate with steel structure instead of wood. With this series of technological improvements, by the end of the 19th century, The production of sulfuric acid in Europe had reached one million tons per year.
<h1 class="pgc-h-arrow-right" > catalyst for a revolution – contact with french sulfuric acid</h1>
Let's talk about the history of contact with the legal sulfuric acid.
In the 1820s, Guy-Lussack made a deep improvement to the lead chamber sulfuric acid process, and added an absorption tower to the process, that is, the Guy-Lusack tower, which can be said to be in the middle of the lead chamber method in this period. But almost at the same time the preparation method of modern sulfuric acid - the prototype and experiment of the contact method
In order to optimize this process, the core is to find a green, efficient way to oxidize sulfur dioxide. Of course, we quickly thought that we could solve this problem by improving the catalyst, and it just so happened that the basic concept of the catalyst was proposed at that time, and the ammonia oxidation reaction we mentioned earlier was also discovered during this period. So in 1831, someone used platinum as a catalyst to try to oxidize sulfur dioxide. Platinum can oxidize sulfur dioxide to sulfur trioxide, which can then be absorbed with water to obtain dilute sulfuric acid. The use of platinum as a catalyst is actually very similar to the technical modification of many of our chemical processes today, which converts the homogeneous catalyst into a heterogeneous catalyst, so that the separation of the catalyst from the product and the loss of the catalyst can be avoided.
This reaction is still very troublesome to apply to engineering. The first is the absorption of sulfur trioxide. People with a little common sense know that sulfur trioxide cannot be absorbed with water, because the process of reacting sulfur trioxide with water to generate sulfuric acid will release a lot of heat, resulting in water evaporation to form acid mist, in fact, the absorption effect is very poor. Of course, it is not difficult to solve this problem, we can use concentrated sulfuric acid to absorb sulfur trioxide, get 98.6% concentrated sulfuric acid or fuming sulfuric acid and then add a small amount of water to get 98% sulfuric acid again, as a circulating liquid for absorption.
Common SO3 absorption process, for so3 absorption process, low concentration of water is easy to enter the gas phase and SO3 combined to form acid mist, SO3 concentration is too high will volatilize the gas phase, so 98.3% is the most suitable absorption concentration. Since the sulfuric acid concentration does not change much before and after absorption, the liquid-gas ratio during the absorption process is actually very large, which reduces the impact of the thermal effect.
The process of solving the sulfuric acid absorption problem was basically opened, and by 1875, the first set of contact sulfuric acid was put into production. However, the emergence of the contact method has not replaced the lead chamber method, and the main problem is still in the catalyst. We know that the catalyst at this time is platinum, and the characteristics of the platinum catalyst are that the catalytic activity is very high, and the disadvantage is that it is very delicate and easy to inactivate. In general, the pre-process process for using precious metal catalysts is as "clean" as possible. For example, in organic synthesis, if there is hydrogenation in the process, then it is necessary to try to avoid some dirty reactions similar to nitrification in front of it, and there are too many nitrification by-products, and it is not certain which one is toxic to the catalyst. Some purification and separation processes also need to be placed before hydrogenation.
This problem exists in the contact method in this period, and we know that the contact method generally uses pyrite combustion to generate sulfur dioxide. Since iron ore, ore associated with sulfur and arsenic and other elements are very normal, after the combustion process these elements will be released in various forms, and sulfur and arsenic are famous catalyst agents. The platinum catalyst itself is very valuable, coupled with the limited life of the inactivation and the overall production cost is not low, so the lead chamber method in this period still dominates. In the subsequent time, people have tried to purify the sulfur dioxide gas for a long time, mainly after dust removal, washing with sulfuric acid and water to remove the pollutants as much as possible. At the same time, the contact method developed slowly, and by the beginning of the 20th century, the lead chamber method had been partially replaced.
Sulfur dioxide occurs in two kinds of pyrite and sulfur, the former has more impurities and more complex treatment, generally including dust removal, pickling, drying, mist removal and other processes. Dust removal uses a cyclone separator to remove large particles, and fine particles are removed with an electric dust collector. The purpose of pickling is to remove arsenic and selenium oxides from gases. An electric mist eliminator is used to remove acid mist generated during washing, and the treated gas is dried into the contact tower.
The real revolutionary advance in contact sulfuric acid lies in the emergence of alum pentoxide catalysts, we know that the early 20th century was the development of metal oxide catalysts, for contact method scientists finally found cheap vanadium pentoxide catalysts in 1914. Under the catalysis of vanadium pentoxide, the most suitable temperature of SO2 is 400-500 °C, the concentration of imported SO2 is about 7%, and the conversion rate can reach more than 97%. The biggest bit of vanadium pentoxide catalyst is cheap leather, the cost is not much lower than the platinum as a precious metal, and the anti-pollution ability of the oxide catalyst is generally stronger than the precious metal. In addition, because the conversion rate of so3 synthesis reaction is very high, and it does not contain impurity gases, it can eventually obtain concentrated sulfuric acid of very high purity, so the lead chamber method is gradually replaced by the subsequent time contact method. After the 1950s, the lead chamber method and the later tower chamber method were basically replaced, and the contact method became the mainstream of modern sulfuric acid production.
Similar to the ammonia oxidation reaction, SO2 oxidation will also emit huge heat, so it is necessary to segment the reaction, cool the gas between each section, and there are many types according to the cooling method, and the cooling pipe set in the reactor is called internal cooling, and the reaction gas is drawn out and cooled with a heat exchanger called external cooling. So2, which is passed cold directly between the two stages of the catalyst, is called the quenching type.
nitric acid
How to prepare nitric acid?
Nitric acid (HNO3) is the basic chemical material of modern industry, and its application in modern industry is very extensive. In fact, nitric acid has long existed in nature, the most important of which is formed by nitric oxide generated on thunderstorms or nitrogen dioxide released by microbial life activities. However, due to the nature of nitric acid and its instability, it cannot exist in nature for a long time, so people need to learn to make nitric acid, and there are many modern methods of making nitric acid.
Molecular bat model of nitric acid
In fact, many regions have saltpeter minerals, saltpeter should also be divided into sodium saltpeter (sodium nitrate) and potassium saltpeter (potassium nitrate). Potassium saltpeter can be used as a potash fertilizer to promote plant rhizome growth and resist lodging. However, because the water solubility is too good, the fertilizer retention ability is very poor, it is easy to lose, and it will cause soil salinization when used more.
Concept diagram of applying fertilizer to plants
The raw materials have been found, and we will learn to prepare nitric acid.
The first method is dry distillation.
The temperature of calcination is very high and requires the support of the equipment. And the device should be sealed to avoid NO2 leakage. A certain industrial base is required to produce in large quantities. However, borrowing the equipment of alchemy and alchemy can barely achieve the purpose of small batch production.
The second method is ammonia oxidation.
Ammonia oxidation method is the main way to produce nitric acid in industrial production, and its main process is to mix ammonia and air (oxygen: nitrogen≈ 2:1) into the hot (760 ~ 840 ° C) platinum rhodium alloy mesh, under the catalysis of the alloy mesh, ammonia is oxidized to nitric oxide (NO). The resulting nitric oxide is used to continue oxidation of the remaining oxygen to nitrogen dioxide after the reaction, and then the nitrogen dioxide is passed into the water to prepare nitric acid.
There is also a reaction is under-electricity - arc method nitric acid process,
Due to the demand for gunpowder in the war, the demand for nitric acid and nitrate can be said to be very urgent.
The main raw materials of the early nitric acid generation method are derived from ore, that is, alum and sodium nitrate, which generate sulfur trioxide by heating alum, dissolve in water to generate sulfuric acid, and then react with sulfuric acid with sodium nitrate, and use the principle of non-volatile acid to prepare volatile acid to generate nitric acid. Of course, in ancient times, it was usually done by a pot method, that is, the green alum and sodium nitrate were directly boiled in a pot, and the mixture made by the ancients without being familiar with the distillation process was actually nitric acid, sulfuric acid and its salt mixture, which could actually be used as raw materials to produce gunpowder or used to dissolve metals. This method was first created by alchemists in the Middle East, and the earliest records appear in the 8th century AD, probably during the Tang Dynasty in China, which was also the heyday of the civilization of the Arab Empire, and the Battle of Qiluo, which marked the conflict between the two major civilizations, took place during this period. It took nearly 800 years for the production of nitric acid to really spread to China, when it was the last year of the Ming Dynasty, the Arab Empire had been dead for more than 300 years, and Europe had begun the Renaissance. Ancient craftsmen at that time called this solution strong water, which was mainly used to dissolve most metals except gold.
This ancient nitric acid refining is a veritable one-pot method, which not only means that all the raw materials are placed in a pot, but also because the iron pot used to refine nitric acid at that time, the reaction process also needs to be heated, and the pot is a mixture of nitric acid and sulfuric acid. Under such extreme conditions, the iron pot will quickly corrode a pot and can only be refined once, which is very wasteful.
Later, with the advent of lead chamber sulfuric acid, the preparation process of nitric acid was simplified, and sulfuric acid was reacted with saltpeter to distill at above 200 °C. In this process, nitric acid is produced in cast iron containers, and then the steamed nitric acid is cooled by a steel cooler. The advantage of this method is that if the sulfuric acid and saltpeter purity are high, they can be directly distilled to obtain more than 96% concentrated nitric acid. One thing is very strange, the natural saltpeter in Europe is generally low in purity, it is said that only Chile produces 96% high-purity saltpeter, in order to make some concentrated nitric acid raw materials transportation to cross half the world, which is obviously not cost-effective, in case Chile to make an embargo or something or not to develop the economy. So as soon as technology developed, Europeans began to study how to make nitric acid by other methods.
The Atacama Desert in northern Chile, a famous saltpeter producer. It is also found in North Africa and California, USA, and is generally found in hot, arid regions. It is generally believed that sodium nitrate is formed by oxidation of nitrogen in proteins to form nitrate and then combined with sodium in soil.
In order to prepare nitric acid, people thought of the method of discharge, and after more than a hundred years of development since the germ of electricity from the beginning of the 18th century, its theory and engineering technology matured in the 19th century. With the use of electricity, electrochemistry also began to rise, in the early 20th century, human beings began to try to react with oxygen in the air through high-voltage arcing, the formation of nitrogen oxides, through absorption and distillation to obtain nitric acid. This process actually simulated the lightning process in nature, and the first to succeed was an Englishman who successfully produced nitrogen oxides by arcing in 1901. Subsequently, a discharge device that produced a stable arc was made, and eventually the Norwegians produced the first industrial production device in 1905.
At that time, the arc generator should be similar to the one in this figure according to the description (the picture comes from the network, do not imitate), through the high-voltage alternating current through two copper rods to discharge the arc, while the arc on both sides of the arc is also added a magnetic field, under the action of the magnetic field, the arc occurs periodic oscillations to form a circular arc, the arc temperature can reach 3000 ° C.
Nitrogen oxides are produced by the arc method, but mainly nitric oxide, nitric oxide is insoluble in water, the conventional operation is to use air to oxidize nitric oxide into nitrogen dioxide, nitrogen dioxide water solubility is relatively good and can react with water to generate nitric acid and nitric oxide. Therefore, the industry generally obtains a dilute nitric acid solution after several series of absorption processes.
The resulting dilute nitric acid solution needs to be purified by distillation to obtain a higher concentration of nitric acid, because nitric acid and water are azeotropic systems, so simply through distillation, the nitric acid concentration can be obtained up to about 68%, if it is necessary to further obtain a higher concentration of nitric acid needs to be further added to the nitric acid solution for distillation, in the arc process generally use concentrated sulfuric acid as a dehydrating agent.
68% concentrated nitric acid is generally a little yellow, because nitric acid sees light decomposition to produce a small amount of nitrogen oxides. 95% nitric acid volatilizes violently, combining with water in the air to form an acid mist.
The advantage of this arc method is that it basically does not consume other raw materials except for electricity. To know that at that time when this method appeared, there was no synthesis of ammonia, to do nitric acid raw materials in addition to saltpeter is air, from this point of view, the arc method occupies a very large advantage. Of course, the disadvantages of the arc method are also very obvious, that is, extreme power consumption, the arc itself is a high energy consumption process, and the energy loss is very serious. Ionizing air, heating gases, emitting strong light and a lot of heat, these unnecessary processes make a lot of energy lost in vain. The nitrogen oxide yield of the arc method is about 80g nitric acid at one degree, if you convert all these electrical energy into nitric acid according to energy balance, you should theoretically get 2.5kg nitric acid. That is to say, if you look at it from the perspective of conversion rate, the conversion rate of this reaction is only 3%, which is an extremely inefficient reaction. In addition, the subsequent purification is also very troublesome, to know that the nitrogen oxide concentration produced by the arc is very low, even if the arc method is continuously improved in the later stage, the NO content in the resulting mixture is only 2.5%, which leads to another very fatal weakness is that the concentration of dilute nitric acid prepared is very low, so the low concentration of dilute nitric acid needs to be purified, then the distillation load is very large, most of the evaporation is water, further increasing the energy loss.
Although the nitrogen fixation efficiency of the arc method was very low, due to the technical problems at that time, people had to adopt this practice. And continuously improve efficiency by improving the arc and reactor structure. By 1925, the world's nitrogen fixed by the arc method reached 340,000 tons, and production reached a historical peak. But at the same time, another more efficient nitric acid production method has gradually begun to take shape, that is, the later ammonia oxidation method. The ammonia oxidation method developed rapidly, completely replacing the arc method in 1932, and the arc method only took 7 years from its peak to its demise.
The arc method is not the most tragic, with the birth of the ammonia oxidation method, there is another method that can be described as a stillborn fetus, that is, the combustion method. The principle of the combustion method is more simple, that is, nitrogen oxides are produced by high temperature action through the combustion process of fuel, and then absorbed to prepare nitric acid. With a reasonable process configuration, a high temperature of 2000 °C can be generated during the re-combustion process, which is enough to generate a large amount of thermal Nox. In addition, the heat burned can also be partially recovered, and if realized, it will save energy compared with the arc method, which is said to have a yield of three times that of the arc method. As a result, just when the Maozi scientist was happily drinking vodka and doing the pilot test, the ammonia oxidation method matured, and the result was no longer followed.
I did not expect that the nitrogen oxide problem that now makes the major thermal power plants tremble is even used as a treasure to synthesize nitric acid decades ago. This figure reveals the relationship between nitrogen oxide generation and furnace temperature, and nitrogen oxides are mainly generated from the nitrogen element brought by the fuel at low temperatures. The higher the temperature, the greater the amount of nitrogen oxides produced by nitrogen oxidation in the air, more than 1800 °C, it will become the main source of nitrogen oxides.
After getting nitric acid, what can it be used for?
1. As an essential raw material for nitrate and nitrate, nitric acid is used to prepare a series of nitrate nitrogen fertilizers, such as ammonium nitrate, potassium nitrate and the like. Transform agriculture and boost productivity.
2, that is, the impure metal is oxidized into nitrate, and then reduced after eliminating impurities. Nitric acid can passivate iron without further corrosion. It can also be used to make nitrogen fertilizer, aqua ream, nitrate, nitroglycerin, nitrocellulose, nitrobenzene, picric acid, etc.
3. Put glycerol in concentrated nitric acid and concentrated sulfuric acid to generate nitroglycerin. It is a very unstable substance that decomposes when struck, producing high temperatures and generating large amounts of gas. Produces violent explosions, so nitroglycerin is a potent explosive.
4, prepared by the reaction of toluene with concentrated nitric acid and concentrated sulfuric acid, is a yellow flake, with the advantages of large explosive power, stable medicinal properties, small hygroscopicity, etc., commonly used as shells, grenades, mines and torpedoes and other explosives, can also be used for mining and other blasting operations.
sodium hydroxide
From causticization to ionic membrane electrolysis – the industrial production of NaOH
After having electricity, you can see my other article [Survival: Strategic Material Reserves---Principle and Acquisition of [Electricity]"
We can do more work in chemicals. Here we will mention a little bit about the thermodynamic nature of chemical reactions.
All chemical reactions have a thermodynamic basis, and the essence of chemical reactions is to rearrange the molecular structure, and this rearrangement requires power, which is what we call free energy. In a chemical reaction, the reactants consume their own free energy to rearrange the molecules to generate reaction products. Therefore, the free energy of the reaction product of the chemical reaction is lower than the free energy of the reactant, which determines the spontaneity of the reaction. As we said, hydrogen reacts with oxygen to produce water, but water generally does not decompose into hydrogen.
The standard Gibbs free energy meter, as long as you know the Gibbs free energy of the reactants and products, you can tell whether the reaction has occurred
However, if the input electrical energy is different for this system, electrical energy is generally considered a high-grade energy that can additionally provide energy for chemical reactions. Therefore, in the case of the participation of electrical energy, the free energy of the reactant can be lower than the free energy of the product. This is the thermodynamic principle of electrochemical reactions.
In the absence of electrochemistry, caustic soda needs to be made from sodium carbonate or grass and wood ash. This is recorded in ancient Chinese or European texts. The core reaction is to react with sodium carbonate or potassium carbonate with calcium hydroxide, because the calcium carbonate generated during the reaction process is precipitated and can be separated from the system, and the reaction can be continuously carried out to finally obtain caustic soda. Calcium hydroxide can be obtained from lime, and the sources of sodium carbonate and potassium carbonate that we mentioned earlier when talking about soda ash can be obtained from grass and wood ash or salt lakes. The specific process is to dissolve soda ash or grass ash in water, add quicklime, quicklime will react after adding a large amount of heat, the solution can reach the boiling point, in this process of reaction. After the end of the reaction, the solution is further clarified to obtain a caustic soda solution after being filtered and vaporized and concentrated. Because caustic soda is also called sodium, this process turns soda ash into a more alkaline substance, so this method is called causticization.
One of the problems with this preparation method was that in the era, sodium carbonate was more widely used than sodium hydroxide. Why? Now in the chemical industry, sodium hydroxide is mainly used to regulate chemical processes such as pH, and in ancient times, the chemical industry was not developed, and sodium hydroxide had no place. At that time, sodium carbonate could already be used in the glass and paper industry, and it could also be used in food. The use of sodium carbonate to produce sodium hydroxide is not economically reasonable. In the later demand for sodium hydroxide gradually expanded, in the history of sodium hydroxide and sodium carbonate demand has been alternating changes, the early demand for sodium carbonate is large, so there is first preparation of caustic soda and then into the carbon dioxide to produce soda ash industry, and there is a period of time to increase the demand for sodium hydroxide caustic method has a place, of course, now the caustic method has been basically eliminated.
Our laboratory master, Scheler, the one who discovered chlorine, used the process of preparing sodium carbonate from sodium hydroxide, when he used salt water to react with lead oxide to produce sodium hydroxide and produce yellow lead yellow. Then sodium hydroxide was used to prepare sodium carbonate, which shows that sodium carbonate is still more valuable than sodium hydroxide at this time.
Later, with the advent of chemical power sources, the experiment of electrolyzing salt water began almost at the same time, and the time of this experiment was about 1802, and the invention of the volta stack was in 1800. During the experiment, it was found that when electrolysis can produce a gas with a pungent odor, and the solution finally appears alkaline, when stoichiometry has been fully developed, a little analysis will know that the reaction process generates chlorine and sodium hydroxide. The efficiency of chemical power supplies during this period was very low, and in order to get electricity we had to react through another chemical, which in itself was not low in cost, so this process actually made no sense. Just like we said a few days ago, a new energy vehicle is said to be able to open with water, but in fact, the production cost of the so-called aluminum catalyst is very high. For electrochemical processes, only if the source of electricity jumps out of the category of chemical power sources, with hydropower, thermal power, solar energy and other sources, then the electrochemical process is meaningful.
So the reaction of electrolyzing salt water waited for nearly 60 years, until the large-scale application of generators was revived. But there is still a long way to go from electrolysis of salt water to the preparation of sodium hydroxide. If you are interested in doing your own electrolysis experiments, you can find that we generally electrolyze sodium hypochlorite solution, that is, disinfectant. Why? Because the chlorine produced by electrolysis can be dissolved in water through sodium hydroxide reaction. Of course, sodium hypochlorite solution has been used very widely, and I know that disinfectant is still being used.
Sodium hypochlorite solution is still in use, we often say 84 disinfectant is sodium hypochlorite solution
If sodium hydroxide is to be prepared, a problem must be solved, that is, how to avoid contact with Cl2 generated by the reaction NaOH. The first way to think of is something like a bridge or diaphragm in the primary battery, which separates the yin and yang poles, and after the separation, the anode produces chlorine gas, and the cathode generates NaOH so that the dissolution of Cl2 and the generation of sodium hypochlorite can be avoided. However, the diaphragm material used in industry was still difficult, and this problem was not solved until 1890, the main way to isolate it using concrete and asbestos. These two materials are equivalent to microporous materials that allow the fluid and the ions in it to pass through, but can block the Cl2 gas, causing the two stages to separate.
Flow chart of electrolytic production of caustic soda by diaphragm method
The diaphragm method was the simplest, but unfortunately the material technology was very weak at that time. The various membrane materials we use now are only available after the development of petrochemicals, and even ceramic membrane materials will have to wait until the 1950s in the 20s. This method is correct in thinking but there are certain problems in engineering. The main disadvantages are two points, first of all, because asbestos is not a strict semi-permeable film material, its role is mainly to isolate chlorine, but there are a small number of hydroxides that can pass through asbestos, and this part will still react with chlorine to generate sodium hypochlorite, resulting in insufficient soda purity. In addition, the concentration of sodium hydroxide in this method cannot be done very high, and the generated lye must be concentrated again. This also makes the later mercury electrode method useful.
The mercury electrode method was proposed in 1892, which is almost the unified period of the diaphragm method. Its core idea is to use mercury as an electrode, and after mercury is used as an electrode, the electrolysis process will directly precipitate sodium on the electrode and form an alloy with mercury. The alloy is collected and then water is added, so that the Na in the alloy will react with the water to form NaOH, and the mercury can be recovered.
The figure shows the basic process of mercury electrode method, which does not require the use of a semi-permeable film to obtain high-purity sodium hydroxide
The disadvantage of this process is the use of mercury, which can theoretically be applied in an infinite cycle. However, it is impossible to have no loss in the actual process, mercury is a highly toxic substance, and the reaction to a sharp increase in temperature during the process of adding water to the electrode will form a vapor, which will damage the health of the operator, which is a serious disadvantage. In addition, mercury in the electrodes during production inevitably dissolves in brine, which is a serious source of pollution if discharged into the environment.
With the development of the process, the caustic soda industry eventually returned to the diaphragm method. The problem of membrane materials was not solved until around 1960. DuPont has developed a perfluorosulfonic acid membrane, which not only isolates chlorine gas, but also has semi-permeability to allow only Na ions to pass through, while blocking Cl ions, so that the electrolysis efficiency is further improved, and now the general caustic soda preparation uses this process.
Perfluorosulfonic acid membrane structure, the main functional group is sulfonic acid group, due to a large number of fluorine ions substitution, the chemical stability and mechanical properties of this membrane are very good.
At this point, the caustic soda electrolysis process is introduced, in this process we found that the reaction also produced chlorine, how will this part of the chlorine be treated? Let's break it down. Hydrochloric acid is obtained.
hydrochloric acid
In one fell swoop , hydrochloric acid synthesis
We obtain sodium hydroxide by electrolyzing saturated saline and at the same time as a by-product we can obtain chlorine and hydrogen. These two gases are now very important chemical raw materials, especially hydrogen, and at this stage, due to the existence of hydrocracking processes, they are basically in short supply. As for chlorine, although it is worse, it is also consumed in the synthesis of polyvinyl chloride. But in the embryonic stage of the chlor-alkali industry, these two gases are a bit embarrassing, chlorine gas is fine, at that time people have learned to use chlorine gas for tap water disinfection, so it can be used as a disinfectant, and the more evil use is that it can also be used as poison gas in the military. Hydrogen is almost a little, according to the reason, there was already synthetic ammonia at that time, you can supplement the gas source of synthetic ammonia, but it is very embarrassing that hydrogen is not easy to transport. Chlorine can be liquefied after pressurization, so that the transportation efficiency is very high, and a bottle can transport a lot. No matter how much hydrogen is pressurized or gas, the molecular weight is still the smallest, there is no one, and the transportation efficiency in the cylinder is extremely low. So to this day, synthetic ammonia plants make their own syngas. Therefore, the hydrogen obtained by electrolysis is generally boiled hot water in the factory, and the excess is sold to various laboratories in cans or used to blow balloons.
Chlorine gas was first found by Scheler when heating manganese dioxide and concentrated hydrochloric acid, chlorine gas is very easy to liquefy, and can be liquefied when pressurized to 6-7 bar at room temperature. Industrial large liquid chlorine tanks are horizontal, when used to use the pressure in the tank to press the liquid chlorine into the gasifier, and then heated with warm water to gasify.
Speaking of the application of chlorine, if the chlorine can be liquefied, it can also be transported, but the more troublesome point is that the chlorine is more corrosive, and there is a certain danger in the transportation process. Therefore, the common practice at that time was to directly inject chlorine into the anti-lime in the chlor-alkali plant to make calcium hypochlorite, which is what we call bleaching powder. The advantage of bleaching powder is that it is solid in itself, although it is still a bit dangerous, but the transportation requirements are much lower. And the use of bleach powder is very convenient, directly sprinkled into the water on the line, so that you can use it, to know that the chlorine gas into the water is the need for special equipment, this kind of thing waterworks and other centralized processing agencies are easy to do, remote areas want to use the family can not always come to a set of it. Therefore, the emergence of bleach powder can be said to be a major gospel in the disinfection industry. I still remember the swimming pool in my hometown county when I was a child, and when I was disinfected, I directly sprinkled bleach powder into it.
But in fact, compared to bleach powder, chlorine gas has a more classic use, that is, it is used to make hydrochloric acid. Hydrochloric acid has been very widely used in the early 20th century, mainly due to the surface treatment of steel and the regulation of acid and alkali in industry. Before the development of the chlor-alkali industry, human beings mainly relied on the principle of strong acids to prepare weak acids to produce hydrochloric acid. The main method used is to react with sodium chloride concentrated sulfuric acid, distill to form hydrogen chloride gas, and then absorb it with water to form hydrochloric acid. Since hydrochloric acid can be continuously removed from the reaction system during this process, the entire chemical reaction can continue.
Another product of this reaction was sodium sulfate, which was discovered in 1658 by the chemist Grobber, hence the time also known as Glauber salt. Originally used as a laxative, sodium sulfate was once used as a universal health product in an era when medicine was not developed. Now sodium sulfate is mainly used in the field of light industry, mainly glass, leather, textile and other industries, and has been widely used in the 19th century.
Now in the chlor-alkali industry, chlorine is generally used to make hydrochloric acid, and this process has two major benefits. First of all, the material is cheap, and sulfuric acid and sodium chloride are not required compared with traditional processes, which are very important chemical raw materials in the late nineteenth and twentieth centuries. In addition, this process can use chlorine gas at the same time to make the hydrogen made by electrolysis also happens to be consumed. Combined with the process of electrolysis to produce caustic soda, the atomic economy of the whole process is very good in today's terms. The sodium chloride and water in the material are completely converted, the chlorine element is converted to hydrochloric acid, the sodium is converted to caustic soda, and the raw material is fully utilized.
Now, the crux of the matter is how to achieve the reaction of chlorine and hydrogen. This reaction was studied after David initially electrolyzed table salt water. Obviously, this reaction can be carried out, but how to stabilize this reaction is indeed difficult. At the laboratory scale, there are two ways to achieve this process, the first is light, and this reaction can be performed under light. However, the process of photochemical synthesis of hydrochloric acid is more violent, in fact, the process of generating chlorine radicals is involved in the middle, and the rate of this reaction is related to the light intensity, the light intensity is small, and the reaction rate is very low. A slightly faster light intensity reacts quickly and is almost uncontrollable. In fact, even now the design and manufacture of photochemical reactors are very difficult, and the industrial synthesis reactions that can be carried out using photochemical processes are very at least.
The reaction of chlorine with hydrogen is a typical free radical process, and the mechanism of this reaction was not clear until 1918, when the chlor-alkali industry began to develop at the end of the 19th century, people only knew that the reaction of chlorine and hydrogen was related to light, and trace amounts of water could promote the reaction.
In order to achieve a stable synthesis reaction between chlorine and hydrogen, it is still necessary to rely on combustion, chlorine itself is more oxidizing than oxygen, and it can react with hydrogen very quickly under the flame. It is important to control the ratio of hydrogen to chlorine during this reaction. Generally speaking, it is necessary to overdose hydrogen, because hydrogen is an inert gas relative to the subsequent process, and a little more can be separated. If the chlorine is excessive, it is serious, and the excess chlorine gas will reduce the quality of the product. From the point of view of the burner, the concentric tube burner is generally used, the combustion tube is injected with chlorine gas inside, and the hydrogen is passed on the outside, so that the hydrogen is wrapped in chlorine for combustion, ensuring that the hydrogen is excessive. The materials involved in the synthesis of hydrogen chloride are all highly corrosive media, so the equipment is made of graphite. In the combustion process flame temperature can reach 1000 degrees, in order to prevent graphite overheating, the container outside the cooling water, to ensure that the container to avoid temperature is not too high. The resulting hydrogen chloride gas is cooled by a graphite cooler at the top of the synthesis tower and with cooling water. This process was first adopted in 1912, and the basic route of the modern chlor-alkali industry was determined.
Hydrogen in chlorine combustion hydrogen excess produces a pale flame (looking around the Internet to find a more similar), if the chlorine excess flame is yellow, production is through this method of process control. There is a mirror on the burner, and the workers are staring at the color on the side, and if the flame is yellowish, they will close the chlorine valve a little smaller. The burners for the industrial hydrochloric acid synthesis process are made of quartz.
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