正构生物烷烃在Pt/ZSM-5催化剂上选择性加氢裂化制备液体生物燃料

Production of liquid biofuels: Normal bio-alkane selective hydrocracking over Pt/ZSM-5 catalysts

开发了一种通过正构生物烷烃在Pt/ZSM-5催化剂上的选择性加氢裂化来制备高品质液体生物燃料的新方法。生产得到的液体生物燃料包含了煤油、汽油和柴油,分离后可直接作为航空燃料或车用燃料使用。以商业ZSM-5分子筛为载体,制备和表征了不同组成的Pt/ZSM-5催化剂。采用转化率、煤汽比和异构率为指标,考察了温度、压力和空速等条件对反应的影响,比较了不同组成时催化剂的催化性能。结果表明:对于同一催化剂,裂化产物异构率随转化率增加而增加;除转化率外,异构率还与酸性位的烯烃被覆度相关;当采用0.7%Pt/ZSM-5(硅铝比50)为催化剂时,在4MPa、320℃、1h-1、氢油体积比1500∶1的反应条件下,原料转化率即可达到82%,产物中煤油含量为43.6%,异构率为1.29,汽油含量为38.0%。

Bifunctional catalysts Pt/ZSM-5 were prepared and tested in the selective hydrocracking of normal bio-alkane for producing liquid biofuels. The liquid biofuels consisted of kerosene, gasoline and diesel, and could be directly used as jet fuel or vehicle fuel after separation. To reveal the effect of catalysts compositions （Pt loading and Si/Al ratio） and operating conditions （temperature, pressure and liquid hourly space velocity） on hydrocracking, parameters such as conversion rate, kerosene/gasoline ratio andiso/n ratio were used. Theiso/n ratio of cracking products increased with increasing conversion rate over the same catalyst. However,iso/n ratio was also related to the alkene coverage of acid sites. An impressive result （conversion rate＆gt;80%, kerosene/gasoline ratio=1.15,iso/n ratio=1.29） was obtained in the laboratory experiment when 0.7%Pt/ZSM-5 catalyst was tested under a relatively mild condition （4MPa, 320℃, 1h？1, H2/oil=1500∶1）.