Propane dehydrogenation(PDH),an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency,has recently attracted extensive attention.The severe deactivation of Pt-based catalysts t...Propane dehydrogenation(PDH),an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency,has recently attracted extensive attention.The severe deactivation of Pt-based catalysts through sintering and coking remains a major challenge in this high-temperature reaction.The introduction of Sn as a promoter has been widely applied to improve the stability and selectivity of the catalysts.However,the selectivity and stability of PtSn catalysts have been found to vary considerably with synthesis methods,and the role of Sn is still far from fully understanding.To gain in-depth insights into this issue,we synthesized a series of PtSn/SiO_(2)and SnPt/SiO_(2)catalysts by varying the deposition sequence and Pt:Sn ratios using atomic layer deposition with precise control.We found that PtSn/SiO_(2)catalysts fabricated by the deposition of SnO_(x)first and then Pt,exhibited much better propylene selectivity and stability than the SnPt/SiO_(2)catalysts synthesized the other way around.We demonstrate that the presence of Sn species at the Pt-SiO_(2)interface is of essential importance for not only the stabilization of PtSn clusters against sintering under reaction conditions but also the promotion of charge transfers to Pt for high selectivity.Besides the above,the precise regulation of the Sn content is also pivotal for high performance,and the excess amount of Sn might generate additional acidic sites,which could decrease the propylene selectivity and lead to heavy coke formation.These findings provide deep insight into the design of highly selective and stable PDH catalysts.展开更多
用微型催化反应装置结合X射线衍射(XRD)、H2化学吸附、NH3吸附-程序升温脱附(NH3-TPD)和H2-程序升温还原等多种物理化学手段研究了丙烷脱氢负载型Pt Sn Na/SUZ-4催化剂中Na+助剂组分的作用。结果表明,Na+组分可中和SUZ-4载体表面的强酸...用微型催化反应装置结合X射线衍射(XRD)、H2化学吸附、NH3吸附-程序升温脱附(NH3-TPD)和H2-程序升温还原等多种物理化学手段研究了丙烷脱氢负载型Pt Sn Na/SUZ-4催化剂中Na+助剂组分的作用。结果表明,Na+组分可中和SUZ-4载体表面的强酸中心、提高催化剂的Pt金属分散度、抑制脱氢产物的裂解和积炭的生成,从而提高催化剂的丙烷脱氢选择性和反应稳定性。但是过量Na+组分的存在会削弱Sn物种与载体之间的相互作用,使其易被还原,导致催化剂丙烷脱氢活性显著下降。展开更多
In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic ...In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic performance was investigated. The as-obtained materials were characterized by XRD, N_2-physisorption, SEM, FT-IR, NH_3-TPD and XPS analyses. The results showed that, with the increase of the weight ratio of Mg(Al)O/ZSM-5, the thickness of Mg(Al)O shell was improved, and the pore structure and physiochemical properties of core-shell materials were directly modified. After introduction of Mg(Al)O, the acidity properties of different materials were significantly suppressed. Meanwhile, more Sn oxide species in Z@MA could facilitate the anchoring of Pt on the support. By effectively employing these modifications, the capacity of the catalysts to accommodate coke was significanty improved and the carbon deposits were migrated from active metal to the carrier. When the weight ratio was equal to 3, the catalyst PtSnNa/Z@MA showed a highest conversion and high selectivity in propane dehydrogenation.展开更多
The Pt Sn/Al_(2)O_(3)catalyst is commonly used in commercial propane dehydrogenation(PDH)processes,but it faces challenges in the deactivation and periodic regeneration due to metal aggregation and coke deposition at ...The Pt Sn/Al_(2)O_(3)catalyst is commonly used in commercial propane dehydrogenation(PDH)processes,but it faces challenges in the deactivation and periodic regeneration due to metal aggregation and coke deposition at high temperatures.Although Al_(penta)^(3+)has been proven to be beneficial for enhancing catalytic stability,bottom-up synthesis protocols usually restrict their applications.Here,a facile post-treatment approach using acetic acid was applied to create color centers(electrons trapped within oxygen vacancies)onγ-Al_(2)O_(3).Notably,the content of Al_(penta)^(3+)was enriched to 18.3%.Then,the pre-established Pt Sn clusters were loaded.The electrons facilitated the formation of ultrafine Pt Sn nanoparticles(~2 nm),and the Al_(penta)^(3+)sites prevented the sintering of Pt Sn by constructing the strong Al_(penta)^(3+)–O–Sn bonds.Furthermore,the catalytic durability of the catalyst prepared by conventional impregnation methods was remarkably extended from 186 h for the color center-free sample to 1,000 h using the HAc–Al_(2)O_(3)support.This facile post-modification was further successfully extended to commercial Al_(2)O_(3)pellets without altering their mechanical properties,highlighting its potential in industrial applications.展开更多
基金supported by the National Natural Science Foundation of China(22102168)the National Science Fund for Distinguished Young Scholars(22025205)+4 种基金the Anhui Natural Science Foundation of China(2108085QB59)Project funded by the China Postdoctoral Science Foundation(BX20190312,2020M671867)the University of Science and Technology of China Youth Innovation Key Fund(YD9990002015)the Fundamental Research Funds for the Central Universities(WK2060000038,WK3430000005)the National Synchrotron Radiation Laboratory(KY2340000135).
文摘Propane dehydrogenation(PDH),an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency,has recently attracted extensive attention.The severe deactivation of Pt-based catalysts through sintering and coking remains a major challenge in this high-temperature reaction.The introduction of Sn as a promoter has been widely applied to improve the stability and selectivity of the catalysts.However,the selectivity and stability of PtSn catalysts have been found to vary considerably with synthesis methods,and the role of Sn is still far from fully understanding.To gain in-depth insights into this issue,we synthesized a series of PtSn/SiO_(2)and SnPt/SiO_(2)catalysts by varying the deposition sequence and Pt:Sn ratios using atomic layer deposition with precise control.We found that PtSn/SiO_(2)catalysts fabricated by the deposition of SnO_(x)first and then Pt,exhibited much better propylene selectivity and stability than the SnPt/SiO_(2)catalysts synthesized the other way around.We demonstrate that the presence of Sn species at the Pt-SiO_(2)interface is of essential importance for not only the stabilization of PtSn clusters against sintering under reaction conditions but also the promotion of charge transfers to Pt for high selectivity.Besides the above,the precise regulation of the Sn content is also pivotal for high performance,and the excess amount of Sn might generate additional acidic sites,which could decrease the propylene selectivity and lead to heavy coke formation.These findings provide deep insight into the design of highly selective and stable PDH catalysts.
文摘用微型催化反应装置结合X射线衍射(XRD)、H2化学吸附、NH3吸附-程序升温脱附(NH3-TPD)和H2-程序升温还原等多种物理化学手段研究了丙烷脱氢负载型Pt Sn Na/SUZ-4催化剂中Na+助剂组分的作用。结果表明,Na+组分可中和SUZ-4载体表面的强酸中心、提高催化剂的Pt金属分散度、抑制脱氢产物的裂解和积炭的生成,从而提高催化剂的丙烷脱氢选择性和反应稳定性。但是过量Na+组分的存在会削弱Sn物种与载体之间的相互作用,使其易被还原,导致催化剂丙烷脱氢活性显著下降。
文摘In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic performance was investigated. The as-obtained materials were characterized by XRD, N_2-physisorption, SEM, FT-IR, NH_3-TPD and XPS analyses. The results showed that, with the increase of the weight ratio of Mg(Al)O/ZSM-5, the thickness of Mg(Al)O shell was improved, and the pore structure and physiochemical properties of core-shell materials were directly modified. After introduction of Mg(Al)O, the acidity properties of different materials were significantly suppressed. Meanwhile, more Sn oxide species in Z@MA could facilitate the anchoring of Pt on the support. By effectively employing these modifications, the capacity of the catalysts to accommodate coke was significanty improved and the carbon deposits were migrated from active metal to the carrier. When the weight ratio was equal to 3, the catalyst PtSnNa/Z@MA showed a highest conversion and high selectivity in propane dehydrogenation.
基金supported from the National Key R&D Program of China(2022YFA1504500)the National Natural Science Foundation of China(92261207,21890752,and 22202164)for financial support+2 种基金support from the Natural Science Foundation of Fujian Province(2023J05006)the Fujian Provincial Chemistry Discipline Alliancethe Fundamental Research Funds for the Central Universities(20720230002)。
文摘The Pt Sn/Al_(2)O_(3)catalyst is commonly used in commercial propane dehydrogenation(PDH)processes,but it faces challenges in the deactivation and periodic regeneration due to metal aggregation and coke deposition at high temperatures.Although Al_(penta)^(3+)has been proven to be beneficial for enhancing catalytic stability,bottom-up synthesis protocols usually restrict their applications.Here,a facile post-treatment approach using acetic acid was applied to create color centers(electrons trapped within oxygen vacancies)onγ-Al_(2)O_(3).Notably,the content of Al_(penta)^(3+)was enriched to 18.3%.Then,the pre-established Pt Sn clusters were loaded.The electrons facilitated the formation of ultrafine Pt Sn nanoparticles(~2 nm),and the Al_(penta)^(3+)sites prevented the sintering of Pt Sn by constructing the strong Al_(penta)^(3+)–O–Sn bonds.Furthermore,the catalytic durability of the catalyst prepared by conventional impregnation methods was remarkably extended from 186 h for the color center-free sample to 1,000 h using the HAc–Al_(2)O_(3)support.This facile post-modification was further successfully extended to commercial Al_(2)O_(3)pellets without altering their mechanical properties,highlighting its potential in industrial applications.
