不同钨源及磷改性复合分子筛载体催化剂的煤焦油加氢裂化性能

以ZSM-5、USY分子筛和Al2O3为载体,分别以偏钨酸铵和磷钨酸为钨源,采用共浸渍法制备NiW加氢裂化催化剂,并以磷为改性助剂进一步对不同钨源的催化剂进行改性。使用BET,NH3-TPD,Py-IR,XRD,XPS,HRTEM等手段对催化剂进行表征,并以中低温煤焦油加氢精制后柴油馏分为原料,在固定床上考察系列催化剂的加氢裂化催化性能。结果表明:采用所制备的NiW加氢裂化催化剂对中低温煤焦油柴油馏分进行加氢改质,芳烃质量分数可降低约10百分点;与以偏钨酸铵为钨源的催化剂相比,以磷钨酸为钨源的催化剂上W和Ni硫化程度更高,因而加氢裂化活性更高,其加氢产物中总芳烃质量分数降低7.06百分点,总饱和烃质量分数提高7.10百分点;磷的加入可提高以偏钨酸铵为钨源催化剂的中强酸强度,提高B酸比例,并提高Ni和W硫化程度,进而提高其加氢裂化活性,其加氢产物中总芳烃质量分数降低7.90百分点,总饱和烃质量分数提高7.94百分点。

COAL TAR HYDROCRACKING ON ZEOLITE-CONTAINING CATALYST PREPARED BY TUNGSTEN FROM DIFFERENT SOURCES AND MODIFIED BY PHOSPHORUS

Ni-W hydrocracking catalysts were prepared by co-impregnation method on the carrier consisted of ZSM-5, USY zeolites and Al2O3 using ammonium metatungstate and phosphotungstic acid as tungsten source, respectively and then modified by phosphorus. The catalysts were characterized by BET, NH3-TPD, Py-IR, XRD, XPS and HRTEM techniques. The hydrocracking performance of the catalysts was evaluated in a fixed-bed reactor, using a hydrotreated diesel fraction obtained from middle/low-temperature coal coking process. The catalyst using phosphotungstic acid as tungsten source exhibits a higher sulfidation degree of W and Ni, resulting in higher hydrocracking activity. The total aromatics contents in the hydrocracked products are decreased by 7.06% and the total saturated hydrocarbon contents are increased by 6.70%, compared with the catalyst using ammonium metatungstate as tungsten source. The addition of phosphorus increases the strength of weak and moderate strong acid, improves the B acid ratio and the sulfidation level of W and Ni of the catalyst prepared using ammonium tungstate as tungsten source, thus enhances its hydrocracking activity. On the P modified catalyst, the total aromatics content in the hydrocracked products was decreased by 7.90% and the total saturated hydrocarbon contents are increased by 7.54%.