中大孔催化裂化催化剂研究进展

Research progress in catalytic cracking catalysts with meso-and macro-pores

发展中大孔型催化剂是催化裂化催化剂的主要发展方向之一,催化裂化催化剂中引入中大孔的主要方法有高岭土酸碱改性法、引入大孔硅铝基材料法、引入介孔分子筛法、原位晶化法和模板法。酸碱改性高岭土的孔结构受原料影响较大,孔径一般小于10 nm;制备大孔硅铝基材料替代拟薄水铝石可有效改善催化剂的孔结构,但应关注对催化剂强度的影响;分子筛中引入介孔又包括水热处理法,酸、碱处理法和引入不稳定位点法,工业应用范围广,但处理过程中易造成Y型分子筛结晶度下降,并缺乏连续、贯通型孔道;原位晶化法是工业上较成功的中大孔催化剂制备方法,但能耗相对高,流程长;模板法可通过改变模板类型、含量对催化剂孔结构调变,但应关注环保及催化剂强度问题。

Research of catalyst rich in meso-and macro-pores is the main development trend of FCC catalyst.At present main ways for preparing catalytic cracking catalysts with meso-and macropores are acid/alkali leaching of kaolin clay,adding macro-porous silica-alumina material,adding meso-porous zeolite,in-situ crystallization and template-preparing method.Macro-pores prepared by acid/alkali leaching of kaolin clay is always heavily impacted by the starting kaolin clay and pore diameter of as-prepared macro-pores are generally less than 10 nm.It is found that macro-porous silica-alumina material can substitute pseudo-boehmite to improve pore structures of FCC catalyst,but the attrition index should be noted.Ways to generate meso-pore in zeolite include hydrothermal treatment,acid/alkali treatment and implanting unstable sites,which apply widely in commercial application.But in these process,crystallinity of Y zeolite are seriously decreased and pore structure is lack of continuity and connectivity.In-situ crystallization is a commercial success for preparing FCC catalyst rich in meso-and macro-pores,but energy-consumption is high and production process is long.Template-preparing method can adjust pore structure by changing template type and content,but environment pollution and attrition index of the catalyst should be noted.