基于分子管理的石油烃定向分离机制及分子筛孔道设计与调控

The hydrocarbons in naphtha are deployed incorrectly and transformed inefficiently in domestic and abroad ethylene and aromatic industry. Based on the molecular management, a novel adsorption material will be designed and prepared with the direction of quantum chemistry calculation of zeolite channel structure and molecular conformations of hydrocarbons. Coupling with the complex ion exchange and chemical liquid deposit, the theory of foundations on the precisely controlling the zeolite channel will be developed. The exchange rate of sodium in the hexagonal prism cage of zeolite Y is improved by the K and Ba complex ion exchange. The zeolite will have high selectivity and capacity through strengthening the porthole deposit and avoiding the internal channel deposit using specially designed deposit agent. The changes of the zeolite channels are monitored by the molecule probes. The diameter of zeolite channel, especially the porthole, will be tuned to match the size of the mono-methyl iso-paraffins. So the zeolite can directionally separate the fraction full of paraffins (n-paraffins and mono-methyl iso-paraffins)from the fraction full of non-paraffins(iso-paraffins with complicated branches, cyclanes and aromatics). The fraction full of paraffin can be used as high quality feed for the steam cracking process to produce ethylene and the fraction full of non-paraffins can serve as high quality feed for the catalytic reforming process to produce aromatics. The utilization efficiency of naphtha can be notably improved through the strategy that suitable molecules for ethylene are for steam cracking and suitable molecules for aromatics are for catalytic reforming.

针对国内外乙烯和芳烃工业存在的石脑油烃类分子错位配置、低效转化的状况，采用分子管理策略，以分子筛孔道结构和烃类分子构象的量化计算为指导设计分子筛孔道，通过复合离子交换和化学液相沉积工艺相耦合，发展分子筛孔道精细调控的基础理论，提高Y型分子筛六方柱笼中Na离子交换度，设计特定的沉积剂体系，强化分子筛孔口沉积，避免孔道内部沉积，确保改性Y型分子筛具有高吸附选择性和吸附容量。采用分子探针监控改性Y型分子筛的孔径变化，使之与单甲基异构烷烃的分子直径相匹配，研制出可以将石脑油烃分子定向分离为富含烷烃组分（正构烷烃和单甲基异构烷烃）和富含非烷烃组分（复杂侧链异构烷烃、环烷烃和芳烃）的高性能吸附材料。富含烷烃组分和富含非烷烃组分分别作为优质裂解和重整原料，实现石脑油分子水平上"宜烯则烯、宜芳则芳"的优化利用。

将烃类族组成定向分离的分子管理策略可以大幅度提高石脑油资源的优化配置水平。为更好地适应乙烯工业和芳烃工业对原料数量的要求，合成了分离石脑油中富含烷烃组分（正构烷烃、单甲基异构烷烃）和富含非烷烃组分（复杂侧链异构烷烃、环烷烃和芳烃）的分子筛吸附剂，并研究了其吸附性能。.基于分子筛的三维孔道模型，采用量子化学方法计算了不同结构烃类分子构象，通过调控Si/Al比合成出了特定的分子筛晶体。结合复合离子交化和化学液相沉积调控分子筛孔道，在25℃下对单甲基异构烷烃的吸附量为3.83g/100g分子筛。石脑油通过分子筛吸附分离过程，合成分子筛可以吸附分离石脑油中含量约30.4%的正构烷烃和约11.8%的单甲基异构烷烃，脱附油的裂解乙烯收率提高约8-10个百分点，吸余油的芳烃潜含量比石脑油提高约10个百分点。.模拟计算了分子筛上的沉积原子分布和微孔受限扩散，研究了化学液相沉积工艺精细调控分子筛孔口直径，考察了不同沉积条件下的沉积量以及相应的分子筛微孔道直径变化。调变后的分子筛具有较高相对结晶度，平均孔径约为0.58nm。.研究了单甲基异构烷烃在成型分子筛上的液相吸附平衡和吸附动力学，获得了吸附温度为10~40℃下2-甲基戊烷、3-甲基戊烷、2-甲基庚烷和3-甲基庚烷的扩散系数，其表观扩散活化能分别为15.57kJ/mol、20.49kJ/mol、17.82kJ/mol和21.68kJ/mol。结构相同时，长碳链单甲基异构烷烃的扩散活化能较大；碳数相同时，3-甲基异构烷烃的活化能高于相应的2-甲基异构烷烃。研究了复合离子交换和化学液相沉积相耦合调节分子筛选择性和吸附容量的作用机理。.研究了合成分子筛的优化成型条件，在拟薄水铝石用量8%、田菁粉用量5%、硝酸浓度5%的条件下，成型后直径为5mm的分子筛颗粒强度为29N。25℃下，2-甲基戊烷的吸附量为0.0351g/g分子筛。.通过基于新型吸附材料的分子管理策略，可以实现石脑油资源分子水平上的宜烯则烯、宜芳则芳，显著提高石油资源的利用效率。