【作者】 孙丽丽；

【导师】 汪颖军；

【作者基本信息】 大庆石油学院 ， 化学工艺， 2008， 硕士

【摘要】 随着国民经济的迅速发展,石油产品的需求不断增加。汽油的消耗每年以2%的速度增长。由此造成的大气污染越来越严重。作为提高汽油辛烷值的重要手段,烷烃异构化越来越受到广泛的关注。因此研究开发高活性高稳定性的烷烃异构化催化剂对提高汽油质量、减少环境污染,改善人类生存环境都有重大的现实意义。本文研究了还原氧化钨基催化剂上正辛烷的异构化反应情况。详细讨论了催化剂的制备条件和反应条件的改变对正辛烷的转化率和异构化选择性的影响。其主要内容如下:(1)实验结果表明,当还原温度为525℃、还原时间为6h、重时空速为1.759h-1、反应温度为300℃WOx催化剂对正辛烷异构化反应表现出最大的催化活性,转化率达到60.21%。通过XRD表征结果推测在正辛烷的异构化反应中,WOx催化剂的催化活性相为WO2,反应的机理可能是传统的双功能机理。BET测定结果发现,还原后的催化剂比表面积明显增加,且具有中孔结构。(2)Ni的掺入不仅明显降低了还原温度,且能明显提高WO3催化剂的催化活性。当焙烧温度为800℃、还原温度为500℃、反应温度为275℃时、2%Ni-WOx催化剂对正辛烷异构化反应表现出最大的催化活性,转化率达到62.15%。通过XRD表征推测2%Ni-WOx催化剂的主要的活性相为WO2,正辛烷在催化剂上是按照传统的双功能机理进行反应的。我们同时考察了Al、Zn、Cr、Cu、Co、Mo、Cd的掺入对WOx催化剂催化正辛烷的活性的影响,其中结果表明金属Al、Zn、Cr、Cu、Co、Mo、Cd的掺入使催化剂的的活性降低。(3)初步考察了担载型WOx/SiO2催化剂对正辛烷异构化反应的催化性能。由于钨物种和载体之间的相互作用,担载型WOx/SiO2催化剂表现出了较差的催化活性,WOx/SiO2催化剂上正辛烷的转化率仅为3%左右。更多还原

【Abstract】 The demand for the petroleum is increasing with the continuous high-speed development of Chinese economy. Consumption of gasoline is increasing over the speed of 2% every year, More and more severe emission pollutions are caused by this.As one of the main routes to produce high-octane gasoline blending components in the crude oil refining industry, alkanes isomerization has drawn much attention throughout the world because it can greatly improve the gasoline quality. For alkanes isomerization, one of the key issues is to develop catalysts with higher activity and higher stability, which has been widely pursued due to its importance both in academic research and in industrial utilization.The objective of our work is to investigate the isomerization of n-octane over tungsten oxide based catalysts. The effects of the preparation and reaction conditions on the conversion and isomerization selectivity of n-octane were studied carefully. The main contents of the thesis were discussed as follows:(1) It was found that the WOx catalyst obtained by H2 reduction at 525℃in a period of 6 hours exhibited a better catalytic activity with the reaction temperature 300℃, WHSV 1.759 h-1. The conversion of n-octane reached 60.21%. The physicochemical properties of catalysts were measured by XRD and BET technique, and the characterized result showed that the active phase of WOx catalyst for n-octane hydroisomerization could be considered WO2. This catalytic behavior was interpreted using the participation of a bifunctional mechanismone on the WO2. By reduction the surface area obviously increased. The catalyst showed the mesoporous character(2) It was indicated that catalytic activity of WOx catalyst for n-octane isomerization was markedly enhanced and the reduction temperature was reduced by incorporation of Ni in the catalyst. It was found that an overall conversion of nearly 62.15% could be achieved on Ni-WOx catalysts, when the calcination temperature was 800℃, the Ni content was 2%, the reduction temperature was 500℃, the reaction temperature was 275℃. The conversion of n-octane on 2%Ni-WOx catalysts was much high than on the WOx catalyst. the selectivity of n-octane on Ni-WOx catalysts was lower than on the WOx catalyst. Characterized studies showed that the active phase of 2%Ni-WOx catalyst for n-octane hydroisomerization could be considered WO2. This catalytic behavior was interpreted using the participation of mechanism: a bifunctional one on the WO2 phase. Incorporation of Al、Zn、Cr、Cu、Co、Mo、Cd to the catalysts did not enhanced the catalytic activity for n-octane isomerization.(3) n-octane isomerization on the WOx/SiO2 catalyst was studied. The WOx/SiO2 catalyst shows lower catalytic activity than bulk WOx catalyst, which can be explained by the interaction between the support and WO3 in WOx/SiO2 catalyst, the conversion of n-octane on the WOx/SiO2 catalyst was only about 3%.更多还原