供氢剂与分散型催化剂在渣油裂化反应中的作用

对分散型催化剂和供氢剂对辽河减压渣油热裂化反应、临氢热裂化反应以及加氢裂化反应的作用进行了研究 ,考察了分散型催化剂、供氢剂在单独或共用时对渣油裂化反应的影响。实验结果表明 ,辽河减压渣油改质中生焦量和渣油转化率的关系与具体的加工过程有关。在同样的生焦量下 ,渣油转化率由大到小依次为 :高氢压催化供氢过程、低氢压催化供氢过程、高氢压催化过程、低氢压催化过程、临氢供氢过程、临氢过程、临氮供氢过程、临氮过程。渣油临氮裂化中 ,供氢剂可以在一定程度上抑制渣油生焦和裂化 ;分散型催化剂既可促进渣油裂化 ,又可作为结焦的晶种使渣油体系提前分相 ,生焦量急剧增加 ,同时对渣油中的供氢剂脱氢有促进作用。在临氢热裂化反应中 ,氢气的参与使渣油的裂化反应和生焦反应受到抑制 ,但氢气对生焦反应的抑制能力远大于对裂化反应的抑制能力。在催化加氢裂化过程中 ,分散型催化剂极大地抑制了生焦反应。分散型催化剂和供氢剂共用可使催化剂的活性有所提高。添加供氢剂后 ,裂化产物中VGO的收率增加 ,生焦量减少 ,而渣油转化率略有降低。

Effects of hydrogen donor and dispersed catalysts on thermal cracking and hydrocracking of Liaohe residue

The dispersed catalysts and hydrogen donor have some effects on thermal cracking, hydrocracking and catalytic hydrocracking of Liaohe residue. The relation between the coke yield and cracking yield of Liaohe residue depends on different reaction systems. With the same conversion, different processings gave the different rates of coking as a following order from large to small:thermal cracking,thermal cracking with H donor,hydrocracking with high hydrogen pressure,hydrocracking with low hydrogen pressure and H donor, hydrocracking with high hydrogen pressure and H donor, catalytic hydrocracking with low hydrogen pressure, catalytic hydrocracking with high hydrogen pressure, catalytic hydrocracking with low hydrogen pressure and H donor, catalytic hydrocracking with high hydrogen pressure and H donor. Addition of pure dispersed catalysts can bring about heavy coking and increase of cracking yield, and dehydrogenation of donors in thermal cracking of residue, but then inhibit coking and dehydrogenation of donors in hydrocracking and catalytic hydrocracking of residue. There is clear synergism between dispersed catalyst and H donor in catalytic hydrocracking of residue, which helps to effectively inhibit coke. In order to improve the deep upgrading of poor residue, four different dispersed catalysts are combined with hydrogen donor to upgrade the residue. In this way, the activities of the four catalysts were improved in comparison with those of the pure catalysts, and the yield of coke substantially decreased, and the yields of VGO increased.