The 2021 Green Mine Science and Technology Award (non-metallic ore, mineral material related fields) application work is organized and reviewed by the Zhongguancun Green Mine Industry Alliance Non-metallic Mine Special Committee, please pay attention to the V letter public number "Powder Technology Network".
Kaolin is a general term for a variety of aqueous aluminosilicatine minerals, with widely distributed resources and significant differences in physicochemical properties due to different origins. Cracking catalytic (FCC) catalysts can be divided into carriers and active components according to their composition. Kaolin is one of the most widely used carrier materials due to its good plasticity, excellent adhesion and excellent stability. When preparing FCC catalysts, the selection of kaolin supports with excellent performance can not only improve the wear strength of the catalyst, resist the ring breaking of the active components by high temperature hydrothermal heat, but also improve the reaction selectivity of the catalyst.
Ren Shihong et al. prepared model catalytic cracking (FCC) catalysts from kaolin soils from three production areas in Suzhou, Guangxi and Georgia, USA, and compared the reaction performance of model catalysts on the ACE evaluation device.
1. Kaolin characteristics
Physical composition: The main components of Suzhou kaolin and Guangxi kaolin are kaolinite and contain a small amount of α quartz; the main components of Georgia kaolin are ground openstone and pearl clay, while kaolinite has a lower content. Ground stone, pearl clay, Elo stone, kaolinite, etc. are the main components of kaolin minerals, and the composition of kaolin is also quite different.
Chemical composition: see table below.
Pore structure: The specific surface area of Suzhou, Guangxi and Georgia kaolin is 22, 27, 26m2/g, and the pore volume is 0.15, 0.17, 0.12cm3/g. composed
Particle size distribution: Georgia kaolin D10 and D50 were 0.174, 0.379 μm, respectively, which were significantly lower than those in Suzhou and Guangxi kaolin, but Georgia kaolin D90 and average particle size were larger, which may be due to the strong agglomeration effect between its particles.
Microscopic morphology: Suzhou kaolin contains both flaky particles and a small number of rod-like particles; Guangxi kaolin grain size is large, and its particles are multi-layered; Georgia kaolin particles are flaky. Among the three types of kaolin, Georgia kaolin has the smallest grain, Guangxi kaolin has the largest grain, and Suzhou kaolin has the middle grain.
2. Catalyst preparation
In the reactor with stirring function, an appropriate amount of deionized water, kaolin and pseudo-thin bauxite are added in turn for full mixing, and after being dispersed evenly, the nitric acid solution with a mass fraction of 0.10% is added to the system, and the temperature is increased to 45 ° C and maintained for 1h in the stirring state; then, the appropriate amount of aluminum sol binder and REUSY molecular sieve slurry are added to the system in turn, and the slurry is fully mixed for 1h; finally, the slurry spray molding is formed into a semi-finished catalyst, and then the model catalyst is prepared by roasting and washing.
3. Discussion of results
The model catalysts prepared by the three kaolins had similar reactivity, Na2O and RE2O3 mass fractions, and the model catalysts prepared by guangxi kaolin had the largest pore volume and wear index, but the specific surface area was the smallest, and the yields of the target products (liquefied gas + gasoline) and by-products (dry gas + coke) were higher than those of the catalysts prepared in Suzhou and Georgia.
Source: Ren Shihong, Fu Manping, Xie Xin, et al. The Influence of Kaolin Properties on the Performance of Catalytic Cracking Catalyst[J].Petrochemical Technology and Application,2021,39(04):247-250", edited by [Powder Technology Network], please indicate the source!