Study On Zn-series Ni-based Catalysts For Hydrogen Production Via Auto-thermal Reforming Of Acetic Acid

Hydrogen,as a clean energy source,is a promising alternative to fossil energy in the 21st century.Biomass is considered a renewable resource for hydrogen production.Bio-oil can be produced by pyrolysis of biomass,which contains oil-phase products and water-phase products with about 30 wt%of acetic acid?HAc?.HAc was then selected as a model component for hydrogen production from bio-oil.The reforming process for hydrogen production generally includes steam reforming?SR?,partial oxidation reaction?POX?and auto-thermal reforming?ATR?.Steam reforming is an endothermic process that requires extra heating during the reaction,while the partial oxidation reaction?POX?of HAc is an exothermic process.The auto-thermal reforming?ATR?,which combines the steam reforming and partial oxidation process to balance the heat supply of the reaction system,is selected for hydrogen production.Hydrotalcite-like Zn-Ni-Al-Fe and Zn-Ni-Zr nickel-based catalysts were prepared and tested in ATR of HAc for hydrogen production;Factors of reaction temperature,oxygen/carbon ratio,and additive of iron were analyzed in ATR of acetic acid,while activity and stability were discussed as well.In this work,Zn_2.4Ni_0.6Al_xFe_1-xO_4.5±?catalysts were prepared by co-precipitation,tested in ATR of HAc,and characterized by XRD,H₂-TPR,BET and XPS.The result showed that the Zn_2.4Ni_0.6Al_0.5Fe_0.5O_4.5±?catalyst presented a better performance in ATR of HAc:the HAc conversion and hydrogen production maintained at 100%and2.39 mol-H₂/mol-HAc,respectively.The characterization results indicated that the better performance can be attributed to the addition of Fe,which was helpful to increase surface area and formation of NiFe alloy after reduction,while resistance to oxidation and coking was improved as well.Zn_xNi_yZrO_4.5±?catalysts were prepared by co-precipitation method,and effect of different Zn,Zr contents on the catalytic activity in ATR of HAc was studied.The results showed that the Zn_1.4Ni_0.6ZrO_4.5±?catalyst performed better in ATR of HAc:the HAc conversion and hydrogen production maintained at 100%and 2.40mol-H₂/mol-HAc,respectively.Characterization indicated that the better performance can be attributed to the stable ZnO and ZrO₂ crystal phases,high specific surface area and stable Ni species during ATR process.