论文总字数：26369字

摘 要

乙烯、丙烯、丁烯等低碳烯烃，对世界工业、农业等发展有着重要作用，因为乙烯是很多重要化工产品的源头原料，人们将乙烯产量作为一个衡量国家的石油化工发展水平的指标。传统低碳烯烃的生产主要依靠石油路线，通过C₂-C₄烷烃或石脑油催化裂解过程来实现。而石油路线生产低碳烯烃条件苛刻，设备投资大，且石油供应量有限。我国天然气储量丰富，因此以天然气作为替代路线制取低碳烯烃尤为重要。

以甲烷为原料经氯甲烷生产低碳烯烃(MeXTO)以其较低的能耗消耗、简单的工艺过程、HCl可循环利用等优点吸引了一大批研究者进行一系列的研究工作。其中，因ZSM-5分子筛催化剂酸量较高，在MeXTO反应中表现出良好的氯甲烷转化率，是一个研究热点。但是因为ZSM-5结构限制，导致催化剂容易积碳失活，需要其他可以提高综合催化性能的分子筛催化该反应。

因此，本论文首先将商品化的HZSM-n(n=5、11、22)分子筛进行理化性能表征，考察了分子筛的晶型结构、酸的分布情况等。其次将分子筛用MeXTO反应中，并和HZSM-5分子筛进行对比，探究催化剂的催化活性、催化剂的稳定性、积碳含量等参数。综合考察了分子筛孔道结构和酸性质对于反应转化率、选择性等的影响。

最后得出HZSM-22分子筛因具有较低的表面酸量，独特的大空间十元环结构，较为狭小的内部空间，有利于丙烯和丁烯的生成，呈现出较好的的催化性能。在450 ºC、空速2.45 h^-1条件下，转化率达93.9%，低碳烯烃总选择性达90.7%，但是稳定性较差。具有HZSM-11分子筛比表面积最大且酸量较大，虽然低碳烯烃选择性最差，但其孔径最大，不容易堵塞孔道，因此催化剂稳定性最长达60 h。通过TG表征，结果表明：在相同的反应时间内，分子筛上产生的积碳量的顺序为HZSM-22大于HZSM-11，故HZSM-11分子筛稳定性大于HZSM-22分子筛。

关键词：ZSM-n 氯甲烷 低碳烯烃 孔道结构 酸性

ABSTRACT

Low-carbon olefins such as ethylene, propylene and butene play an important role in the development of the world's industry and agriculture. Because ethylene is the source of many important chemical products, ethylene production is used as an indicator to measure the country's petrochemical development level. The production of traditional low-carbon olefins is mainly based on the petroleum route and is achieved by a C₂-C₄ alkane or naphtha catalytic cracking process. Moreover, the petroleum route produces harsh conditions for low-carbon olefins, large equipment investment, and limited oil supply.China's natural gas reserves are abundant, so it is particularly important to use natural gas as an alternative route to produce low-carbon olefins.

The use of methane as a raw material to produce low-carbon olefins (MeXTO) from methyl chloride has attracted a large number of researchers to conduct a series of research work with its low energy consumption, simple process, and HCl recycling. Among them, the most widely used catalyst is ZSM-5 molecular sieve, because its higher acid amount shows good conversion of methyl chloride in the MEXTO reaction. However, due to the structural limitations of ZSM-5, the catalyst is easily deactivated by carbon deposition, and other molecular sieves that can improve the overall catalytic performance are needed to catalyze the reaction.

Consequently, in this paper, the physical and chemical properties of HZSM-n (n=5, 11, 22) molecular sieves were first characterized. The crystal structure and acid distribution of HZSM-n molecular sieve were also analyzed.And acid center strength and so on. Furthermore, the molecular sieve was reacted with MeXTO and compared with HZSM-5 molecular sieve to explore the catalytic activity of the catalyst; stability of the catalyst; carbon content and other parameters. The effects of molecular sieve pore structure and acid properties on reaction conversion rate and selectivity were analyzed.

Finally, it is concluded that HZSM-22 molecular sieve has a lower surface acidity, a unique large space ten-membered ring structure, and a relatively narrow internal space, which is beneficial to the formation of propylene and butene, and exhibits good catalytic performance. At 450 ^oC and a space velocity of 2.45 h^-1, the conversion rate was 93.9%, and the total selectivity of low-carbon olefins was 90.7%, but the stability was poor. The HZSM-11 molecular sieve has the largest specific surface area and large acid amount. Although the low carbon olefin has the worst selectivity, it has the largest pore diameter and is not easy to block the pores, so the catalyst stability is up to 60 h. Characterization by TG showed that the order of carbon deposition on the molecular sieve was HZSM-22 greater than HZSM-11 in the same reaction time, so the stability of HZSM-11 molecular sieve was larger than that of HZSM-22 molecular sieve.

KEYWORDS：HZSM-n；Chloromethane；Light olefins；Tunnel structure；Acidity

目 录

摘 要 I

ABSTRACT II

第一章 文献综述 1

1.1 氯甲烷制低碳烯烃概述 1

1.2 氯甲烷制低碳烯烃机理 1

1.3 氯甲烷制烯烃催化剂研究进展 2

1.3.1 ZSM-n(n=5,11,22,23,35)催化剂 3

1.4 论文思路及研究内容 8

第二章 实验部分 9

2.1 实验原料及试剂 9

2.2 主要实验仪器及设备 10

2.3 催化剂的表征 10

2.3.1 X射线衍射(X-ray diffraction) 10

2.3.2 氮气吸附脱附(Adsorption and Desorption of N₂) 10

2.3.3 吡啶吸附红外光谱(Py-IR) 11

2.3.4 氨气程序升温脱附(NH₃-TPD) 11

2.3.5 热重分析(Coking Analysis) 11

2.4 催化剂的性能评价 12

2.4.1 性能评价及装置流程图 12

第三章 实验结果讨论 14

3.1 HZSM-n分子筛对MeXTO催化性能的研究 14

3.1.1 HZSM-n理化性质表征 14

3.1.4 HZSM-n分子筛对MeXTO反应催化性能的影响 17

第四章 结论与展望 23

参考文献 24

致谢 29

第一章 文献综述

1.1 氯甲烷制低碳烯烃概述

低碳烯烃作为合成塑料、纤维等化工产品的原料，推动我们化工行业发展起着重要的作用 。丙烯可以生产聚丙烯，丙烯腈、丙酮、树脂、橡胶等^[1]；乙烯生产聚^[2]乙烯、氯乙烯、乙醛、合成纤维等。传统低碳烯烃的生产主要依靠石油路线，通过C₂-C₄烷烃或石脑油催化裂解过程来实现^[3-6]，而石油资源是不可再生资源，石油资源的枯竭需要减少对石油的依赖。因此，寻找可替代路线制取低碳烯烃尤为重要。

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