ZnW/β中ZnO含量对其催化四氢萘加氢裂化反应性能的影响

摘要/Abstract

摘要： Zn的引入不仅可以调控β分子筛的酸性质,而且还会影响催化剂的加氢活性。为了研究Zn的引入对催化剂加氢裂化反应性能的影响,利用浸渍法合成了一系列不同ZnO含量的ZnW/β加氢裂化催化剂,并对其物理化学性能进行了分析表征。研究了ZnO含量对其催化四氢萘加氢裂化制备BTX(苯/甲苯/二甲苯)催化性能的影响。结果表明,最高BTX收率随着ZnO含量的增加先升高(质量分数<1%时)后降低(质量分数>1%时),这是由于随着ZnO含量的增加,ZnW/β催化剂的强酸量和总酸量明显减小,抑制了四氢萘的过度裂化。而当ZnO的负载量达到1%(质量分数)后,ZnO与WO₃反应会生成非活性组分ZnWO₄晶体,非活性组分ZnWO₄晶体的生成量随着ZnO的含量增大而增大,降低了催化剂中加氢活性组分WO₃的含量,导致ZnW/β催化剂的加氢中心与酸中心匹配不佳。ZnO负载量为1%的ZnW/β催化剂在反应空时为0.36 h时达到最高的BTX收率(41.57%,质量分数),说明该催化剂的酸量适中且加氢中心与酸中心匹配最佳。因此,催化剂金属中心与酸中心合适的匹配及适中的酸强度是提高BTX收率的关键。

关键词: 四氢萘, 加氢裂化, BTX(苯/甲苯/二甲苯), ZnO, ZnWO₄, β分子筛

Abstract: The introduction of Zn can not only adjust the acid properties of β zeolite, but also affect the hydrogenation activity of catalyst. A series of ZnW/β hydrocracking catalysts with different ZnO contents were synthesized by impregnation method, and their physicochemical properties were analyzed in order to study the effect of Zn introduction on the hydrocracking reaction performance. The effect of ZnO content in the ZnW/β catalysts on the catalytic performance of hydrocracking of tetralin to prepare BTX (benzene/toluene/xylene) was investigated. The results show that the highest BTX yield firstly increases (<1%, mass fraction) and then decreases (>1%, mass fraction) with the ZnO content. The yield of BTX increases because the amount of strong acid and total acid of ZnW/β catalyst decreases obviously with the increase of ZnO contents, which inhibits the excessive cracking of tetralin. However, the yield of BTX decreases because the ZnO react with WO₃ to form inactive ZnWO₄ crystals when the load of ZnO reaches 1%(mass fraction), and the amount of inactive ZnWO₄ crystals increase with the increase of ZnO contents, and the ratio of inactive ZnWO₄ crystals to WO₃ gradually increases, leading to decrease of the number of WO₃ hydrogenation active centers. As a result, the hydrogenation center of ZnW/β catalyst does not match well with the acid center. The ZnW/β catalyst with 1% ZnO loadings has the highest BTX yield (41.57%, mass fraction) when the reaction space time is 0.36 h, which indicates that the acid amount of the catalyst is moderate and the matching between the hydrogenation center and the acid center is the best. Therefore, suitable matching of catalyst metal center and acid center and moderate acid strength are the key to improve the yield of BTX.

Key words: tetralin, hydrocracking, BTX(benzene/toluene/xylene), ZnO, ZnWO₄, β zeolite

中图分类号:

O643.38

王磊, 党辉, 张燕挺, 陈胜利. ZnW/β中ZnO含量对其催化四氢萘加氢裂化反应性能的影响[J]. 人工晶体学报, 2023, 52(2): 334-344.

WANG Lei, DANG Hui, ZHANG Yanting, CHEN Shengli. Effect of ZnO Content in ZnW/β on Its Catalytic Performance for Tetralin Hydrocracking Reaction[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2023, 52(2): 334-344.

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