Chemical Industry and Engineering Progress ›› 2024, Vol. 43 ›› Issue (3): 1309-1317.DOI: 10.16085/j.issn.1000-6613.2023-0447

• Industrial catalysis • Previous Articles    

Particle size regulation of HZSM-22 and Pt/HZSM-22 for n-dodecane hydroisomerization

CHEN Feng1(), WANG Xuande3, HUANG Wei1, WANG Xiaodong1(), WANG Yan2()   

  1. 1.State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
    2.College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
    3.Guoneng Shouguang Power Generation Co. , Ltd. , Weifang 262714, Shandong, China
  • Received:2023-03-23 Revised:2023-07-01 Online:2024-04-11 Published:2024-03-10
  • Contact: WANG Xiaodong, WANG Yan

HZSM-22的粒径调控及Pt/HZSM-22的正十二烷加氢异构催化性能

陈风1(), 王宣德3, 黄伟1, 王晓东1(), 王琰2()   

  1. 1.太原理工大学省部共建煤基能源清洁高效利用国家重点实验室,山西 太原 030024
    2.太原理工大学化学工程与技术学院,山西 太原 030024
    3.国能寿光发电有限责任公司,山东 潍坊 262714
  • 通讯作者: 王晓东,王琰
  • 作者简介:陈风(1997—)女,硕士研究生,研究方向为分子筛的制备及催化。E-mail:1227679716@qq.com
  • 基金资助:
    国家重点研发计划(2020YFB0606405);山西省基础研究计划(20210302123197);山西省重点研发计划(201803D121043)

Abstract:

ZSM-22 zeolite crystals with different c-axis lengths were synthesized by using supersaturated solution method under static hydrothermal conditions and adjusting the water content in the synthetic solution. The as-synthesized ZSM-22 zeolite crystals were characterized by XRD, SEM, N2 physical adsorption, NH3-TPD and Fourier transformed infra-red spectroscopy of pyridine adsorption(Py-FTIR). By loading Pt on the ZSM-22 zeolite crystals, the Pt/ZSM-22 bifunctional catalysts were prepared, in which ZSM-22 zeolite crystals played the role of acid supports and the 0.5% Pt acts as (de)hydrogenation active sites. The hydroisomerization of n-alkanes was carried out with n-dodecane as the probe molecules. The effect of water content in the zeolite synthesis solution on the hydroisomerization performance of Pt/ZSM-22 catalyst was investigated. The results indicated that the less the water, the smaller the ZSM-22 crystals. However, a few cristobalite and ZSM-5 crystals were formed when the content of water in the synthetic solution was reduced to a certain value. HZSM-22 synthesized in the solution with the molar composition of SiO2∶Al2O3∶K2O∶DEA∶H2O=1∶0.01∶0.08∶0.29∶28 showed the highest medium and strong Brønsted acid amount in the three HZSM-22 samples, and shorter c-axis length. The bifunctional catalyst Pt/HZSM-22 prepared with this kind of HZSM-22 crystals showed the best catalytic performance. The conversion of n-dodecane was 73.24%, the yield of iso-alkanes was 57.92%, and the selectivity of iso-alkanes was 79.09%.Moreover, the selectivity of mono-branched iso-dodecane with methyl branching positioned in the center of the chain, 5-methylundecane, was up to 17.66% at 320℃.

Key words: supersaturated solution method, ZSM-22 molecular sieve, c-axis length, n-dodecane, hydroisomerization

摘要:

通过调控合成液中的水含量,采用过饱和溶液法,在静态水热条件下合成了三种不同c轴长度的ZSM-22分子筛,对其进行了X射线衍射、扫描电子显微镜、N2物理吸附、NH3-程序升温脱附和吡啶吸附傅里叶变换红外光谱(Py-FTIR)表征。并以所制备的ZSM-22分子筛为酸性载体,在其上负载0.5%(质量分数)的金属Pt作为加(脱)氢活性位点,制备成Pt/ZSM-22双功能催化剂。以正十二烷为探针分子,进行正构烷烃加氢异构化反应,考察了分子筛合成液中水含量对Pt/ZSM-22催化剂加氢异构化性能的影响。结果表明,随着合成液中水含量减少,ZSM-22分子筛粒径减小。但是当水含量低到一定值时,会有方英石和ZSM-5杂晶生成。当分子筛合成液摩尔组成为SiO2∶Al2O3∶K2O∶DEA∶H2O=1∶0.01∶0.08∶0.29∶28时,获得的HZSM-22在所合成的三种分子筛中拥有最多的中、强Brønsted酸量以及较短的c轴长度,对应的双功能催化剂Pt/HZSM-22表现出最佳催化性能。在320℃时,正十二烷转化率为73.24%,异构烷烃收率为57.92%,异构烷烃选择性为79.09%,尤其是中心位置甲基异构体5-甲基十一烷的选择性达到了17.66%。

关键词: 过饱和溶液法, ZSM-22分子筛, c轴长度, 正十二烷, 加氢异构化

CLC Number: 

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