Application Study Of Silica Sol In Catalytic Cracking Catalyst

Binder is an important component of semi synthetic FCC catalyst,which not only plays a role in the formation with other components of the catalyst,but also provides some pore structure and activity for the catalyst,and its performance,in some extent,has some influence on the performance of FCC catalyst.Common binders as we know are aluminum sol,silica sol,silica aluminum sol,etc.Since 1960,the exploration of silica sol by foreign researchers has begun.However,the research of silica sol in China is more than 10 years later than that in other countries,so it was not produced on a large scale until the 1980 s.Nowadays,in order to cope with the heavy and poor quality of catalytic raw materials,domestic FCC catalysts pay more attention to the improvement of heavy oil cracking capacity in research and development,thus increasing the yield of light oil.However,in terms of selectivity,neither coke nor gasoline has achieved ideal results,so it is particularly important to improve the selectivity of FCC catalysts.Silica sol has good cohesiveness.The development of FCC catalyst using silica sol as binder has important practical significance for increasing its type and improving its cracking performance.In this paper,silica sol and aluminum sol with different acid and alkali properties were used as raw materials to prepare FCC catalyst for silica sol,aluminum sol and silica alumina sol as binder.Meanwhile,the reasons for gel formation of silica sol and silica alumina mixed sol were also explored.The wear index of the prepared catalyst was determined,and suitable catalyst samples were selected.The catalyst samples before and after treatment were characterized by pyridine adsorption infrared spectroscopy,X-ray diffraction(XRD),X-ray fluorescence spectrometry(XRF),low temperature nitrogen adsorption and water drop method.Meanwhile,its micro reactivity and small-scale catalytic cracking reactor(ACE)were evaluated.The research indicates that the catalyst using silica-aluminum mixed sol as binder has larger specific surface area,activity,conversion rate,gasoline yield and total liquid yield,smaller pore volume and B-acid and L-acid content,and stronger resistance to Ni and V pollution than that using pure aluminum sol as binder.Before aging,the cell constants of silica-aluminum mixed sol catalysts are basically the same as that of aluminum sol catalysts.After aging,the cell constants of silica-aluminum mixed sol catalysts remain unchanged,but the Al content in catalysts increases and the Si content decreases,which may be due to the destruction of skeleton silicon during aging.By analyzing the performance of FCC catalysts prepared with different binders,this paper provides a theoretical basis and experimental reference for exploring a kind of FCC catalyst with good strength,large pore structure,high acidity and high activity.