Study On Zn-Ni-Cr-O And Ni-Mn-Y-O Catalyst For Hydrogen Production From Acetic Acid

Hydrogen energy is one effective solution to address energy demand.Acetic acid（HAc）,the aqueous component of biomass oil,is used to produce hydrogen by auto-thermal reforming（ATR）,which has the advantages of heat self-sustainability and high hydrogen production efficiency.Ni-based catalysts are favorable for the activation of C-C bond and C-H bond in the HAc molecule,and have higher activity for hydrogen production.But Ni-based catalysts is easily deactivated in the reaction due to oxidation,sintering,or carbon deposition.In this paper,a series of transition metal-promoted Ni-based catalysts have been developed and used in the ATR of HAc.And various characterization methods have been used to explore the catalytic structure-activity relationship,which has effectively improved the reaction activity and stability of the catalysts.Zn_xNi_yCr O_m±δcatalysts were prepared by a co-precipitation method via precursors of hydrotalcite-like structure（LDHs）.After calcination and reduction,t-Ni Zn intermetallic compounds（IMC）were formed.During the ATR of HAc,the intermetallic compound was converted into Ni/（amorphous-Zn O）-Zn Cr₂O₄ species.And Ni-Zn-Cr-O complex oxide structure with strong interaction is formed,in which the Ni species are evenly distributed and highly dispersed,which promote the resistance to sintering,carbon deposition and oxidation of the catalysts,and effectively improves the activity and stability of the catalysts.The obtained Zn_2.37Ni_0.63Cr O_4.5±δcatalyst exhibited excellent activity and stability in the 45-hour testing in ATR of HAc:the conversion rate of HAc is maintained at 100%,accompanied with the hydrogen yield is stable at2.7 mol-H₂/mol-HAc.The Ni Mn Y composite oxide catalysts were prepared by a hydrothermal synthesis method,and the proper amount of Mn species promoted the formation of YNi O₃perovskite structure,so that Ni0 species were highly dispersed after reduction.At the same time,Mn-O compounds with various valence states had more lattice defects,and the oxygen vacancies generated by these lattice defects can activate OH*and H*species,which is beneficial to vaporize carbon.And the introduction of Y₂O₃ increased the conversion rate of CH₄ and improved the selectivity to H₂.The obtained Ni Mn Y catalyst exhibited excellent activity of HAc conversion and hydrogen yield in ATR of HAc:HAc conversion rate was close to 100%and remained stable;the hydrogen yield was stable at 2.7 mol-H₂/mol-HAc;and the formation of coke was suppressed.