加工俄油常渣催化裂化催化剂中Y型分子筛的研究

Study on Y Zeolite for FCC Catalysts used for Russian Oil Atmospheric Residue Processing

由于俄罗斯原油进口量不断增长,俄油常渣在国内催化裂化原料组成中所占的比例逐渐提高。分析表明,与国内大庆原油常渣相比较,俄罗斯原油常渣的主要特点是饱和烃含量低(48.6%,质量分数),芳烃含量高(43.9%,质量分数),重金属含量高(Ni+V为25.2μg/g),可裂化性能差,更易于生焦。所以,采用催化裂化手段加工俄油常渣需要解决的关键技术问题是降低产品中焦炭的选择性,要求开发出高活性、低生焦催化剂,其中,催化剂活性组分Y型分子筛是影响催化剂焦炭选择性最关键的因素。为此设计并进行了多组实验,采用不同性质的Y型分子筛,制备成催化剂,并对所制备的催化剂进行反应性能评价,包括晶胞常数、结晶度、Na_2O含量、孔结构及晶粒尺寸对产品中焦炭选择性的影响规律,结果表明,晶胞常数较低、结晶度较高、Na_2O含量较低、介孔比例较高和晶粒尺寸较小的Y型分子筛有利于降低焦炭选择性,是加工俄油常渣催化裂化催化剂较为理想的活性组分。

Owing to the increasing import of Russian oil,the proportion of Russian oil atmospheric residue in the composition of domestic FCC feedstocks has gradually increased.The analysis shows that the main charac-teristics of Russian oil atmospheric residue are low saturated hydrocarbon content(48.6 w%),high aromatic hydrocarbon content(43.9 w%),high heavy metal content(Ni +V,25.2μg/g),poor crackability and easier coking compared with the domestic Daqing oil atmospheric residue.Therefore,the key technical problem in processing Russian oil atmospheric residue by catalytic cracking is to reduce the coke selectivity in products,which requires the development of high activity and low coke generation catalysts.Among all the elements,Y zeolite is the most critical factor affecting the coke selectivity of catalysts.A series of experiments were designed and carried out to prepare catalysts with Y zeolites with different properties,and the reaction performance of the prepared catalysts was evaluated.The effects of physical and chemical properties of Y zeolite,including lattice constant,crystallinity,Na2O content,pore structure and grain size,on coke selectivity were studied in detail.The results showed that Y zeolite with lower lattice constant,higher crystallinity,lower Na2O content,higher mesoporous ratio and smaller grain size is beneficial to reduce coke selectivity and is an ideal active component of the FCC catalysts for processing Russian oil atmospheric residue.