Inorganic Chemicals Industry ›› 2024, Vol. 56 ›› Issue (3): 144-154.doi: 10.19964/j.issn.1006-4990.2023-0333

• Catalytic Materials • Previous Articles    

Effect of promoter on physicochemical properties and catalytic performance of ZnO/ZrO2

REN Qixia1,2,3(), YANG Kun1,2,3, LIU Fei1,2,3(), YAO Mengqin1,2,3, CAO Jianxin1,2,3   

  1. 1.School of Chemistry and Chemical Engineering,Guizhou University,Guiyang 550025,China
    2.Guizhou Key Laboratory for Green Chemical and Clean Energy Technology,Guiyang 550025,China
    3.Guizhou Engineering Research Center of Efficient Utilization for Industrial Waste,Guiyang 550025,China
  • Received:2023-06-16 Online:2024-03-10 Published:2024-03-14
  • Contact: LIU Fei E-mail:995985627@qq.com;ce.feiliu@gzu.edu.cn

Abstract:

CO2 hydrogenation to methanol is an effective way to achieve the goal of carbon neutrality.Although the reported ZnO/ZrO2 catalysts have high activity and stability,their catalytic performance are expected to be further improved.A series of Ma-ZnO x /ZrO2 catalysts with different elements doping were prepared by the impregnation method,and it was found by evaluation that only Ga promoted the catalytic CO2 hydrogenation to methanol by ZnO/ZrO2 catalyst.Among them,5%Ga-ZnO x /ZrO2 catalyst showed excellent catalytic performance.At the reaction conditions:P=3 MPa,T=320 ℃,V(H2)∶V(CO2)=4∶1 and gas weight hourly space velocity(WHSV)=24 000 mL/(g∙h),the CO2 conversion of 5%Ga-ZnO x /ZrO2 catalyst was 7.2%,the methanol selectivity was 81.0% and the methanol space-time yield was up to 410 mg/(g∙h),which was 1.26 times higher than that of the ZnO/ZrO2.And there was no significant decay in the catalytic performance within 100 h of reaction.X-ray photoelectron spectrometry(XPS) and electron paramagnetic resonance(EPR) characterization showed that doping with the appropriate amount of Ga promoter could promote the formation of oxygen vacancies in the catalyst.H2 temperature programmed reduction(H2-TPR),temperature-programmed desorption of the preabsorbed CO2/H2(CO2/H2-TPD) results showed that the doping of the Ga promoter enhanced the activity of the active sites of the ZnO/ZrO2 catalyst,and the Ga-ZnO x /ZrO2 catalyst exhibited a stronger capacity for the adsorption and activation of CO2 and H2.The in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS) results showed that the synthesis of methanol by each catalyst followed the formate-methoxy pathway,and the incorporation of Ga promoter facilitated the formation of methanol intermediates and was favorable for the conversion of HCOO* species to CH3O* species,thus improving the methanol yield.

Key words: CO2 hydrogenation, methanol, ZnO/ZrO2, Ga promoter, oxygen vacancy

CLC Number: