摘要
炔烃制备烯烃在聚合物和精细化工工业中具有至关重要的地位,但在平衡选择性和活性方面仍存在相当大的难题。本文通过使用不同的硫源成功合成了几种钯-硫纳米片(Pd-S NSs),并研究了表面硫物种对炔烃选择性加氢催化效率的影响。在这些催化剂中,以1,4-苯二硫醇(PT)为硫源的Pd-S-PT NSs/C在苯乙炔加氢2h后表现出较高的苯乙烯选择性(92.3%-96.7%)。Pd-S-PT NSs的烯烃选择性增强的原因在于Pd到S的电子转移较差,以及表面独立存在的S^(0)物种,保持了较高的加氢活性,同时避免了高氧化态的S(S^(4+))引起的过度加氢。该研究不仅开发了高效的炔烃加氢催化剂,还推动了对催化表面精确控制的基础研究。
Olefins play a crucial role as fundamental raw materials in organic synthesis,particularly in the production of polyolefins and synthetic rubber.The conversion of alkynes to olefins is pivotal in both the polymer and fine chemical industries.However,this process faces significant challenges in terms of equilibrium selectivity and activity.The inherent low solubility of hydrogen,coupled with the thermodynamic ease of hydrogenating intermediate olefins compared to alkynes,contributes to a decline in olefin selectivity due to further hydrogenation leading to alkanes.Palladium-based catalysts,widely used for hydrogenation,exhibit robust hydrogen adsorption but lack selectivity.Researchers commonly modify catalyst structures by introducing other metals or nonmetals to create intermetallic compounds,aiming to enhance olefin selectivity.This study focuses on synthesizing palladium-sulfur nanosheets(Pd-S NSs)using various sulfur sources to explore the impact of surface S species on the catalytic efficiency of selectively hydrogenating alkynes.Among these,Pd-S-PT NSs/C,utilizing 1,4-benzenedithiol(PT)as the sulfur source,demonstrated high styrene selectivity(92.3%-96.7%)following phenylacetylene hydrogenation for 2 h,showing notable selectivity for different alkynes’end-groups.Contrastingly,Pd-S-TU NSs/C,with thiourea(TU)as the sulfur source,exhibited poor olefin selectivity(72.4%).X-ray photoelectron spectroscopy(XPS)revealed that the improved olefin selectivity in Pd-S-PT NSs/C was attributed to hindered electron transfer from Pd to S,as well as the presence of surface S^(0) species,maintaining high hydrogenation activity while avoiding over-hydrogenation induced by oxidized S species(S^(4+)).In situ diffuse reflectance Fourier transform infrared spectroscopy(DRIFTS)demonstrated weak styrene adsorption on Pd-S-PT NSs,inhibiting further hydrogenation to ethylbenzene.The ease of styrene desorption on Pd-S-PT NSs,indicated by reduced adsorption strength with increasing desorption temperature,highlighted high olefin selectivity.Conversely,stronger styrene adsorption on Pd-S-TU NSs facilitated additional hydrogenation to produce ethylbenzene,suggesting that the presence of additional S4+species hindered improved styrene selectivity.This study not only introduces efficient catalysts for olefin hydrogenation but also advances fundamental research on precisely controlling catalytic processes,particularly focusing on the nuanced control of catalytic surfaces.
作者
张伟晗
王梦露
贾安康
邓威
白树行
Weihan Zhang;Menglu Wang;Ankang Jia;Wei Deng;Shuxing Bai(Institute for Sustainable Energy and Resources,College of Chemistry and Chemical Engineering,Qingdao University,Qingdao 266071,Shandong Province,China;School of Optoelectronic Materials and Technology,Jianghan University,Wuhan 430056,China)
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2024年第11期23-24,共2页
Acta Physico-Chimica Sinica
基金
国家自然科学基金项目(22102078)
山东省自然科学基金(ZR2021QB091)
青岛大学启动资金资助项目。
关键词
钯-硫纳米片
表面硫物种
炔烃加氢
烯烃
选择性
Palladium-sulfur nanosheets
Surface sulfur species
Alkyne hydrogenation
Alkene
Selectivity
