Hydrogen Production Via Steam Reforming Of Bio-oil Derived Model Compound Acetic Acid Over Ti-modified Ni/ATP Catalysts

Hydrogen energy is considered to be the most promising clean energy in the 21 st century.Building a low hydrocarbon economy can not only accelerate the transformation of the energy industry,but also play a vital role in the whole process of energy conservation and emission reduction.Hydrogen production from biomass resources with green,renewable and zero carbon dioxide emission in the conversion process is of great significance to achieve "emission peak and carbon neutral".At present,hydrogen production from bio-oil reforming is still in the basic research process,because the complex composition of bio-oil limits the understanding of the mechanism of hydrogen production from bio-oil reforming.It has been widely recognized by many scholars to reveal the mechanism of hydrogen production by steam reforming with bio-oil model such as acetic acid.Aiming at the key scientific problems of catalyst agglomeration,sintering and coking in the process of hydrogen production from bio-oil reforming,this paper proposed to use the green economic nano-fiber structure of attapulgite as the carrier,Ni as the active phase,by doping the transition metal Ti modification,to prepare a catalyst with high activity and high stability.The mechanism of acetic acid steam reforming with Ni/ATP modified by Ti to produce hydrogen was revealed.The main research contents and conclusions are as follows:(1)Ti modified Ni/ATP catalysts were prepared by coprecipitation method with attapulgite(ATP)as support and different Ti precursor salts.The effects of the introduction of Ti and the use of different Ti precursor salts on the properties of the catalysts were systematically studied by N2 adsorption-desorption,XRD,H2-TPR,XPS,FTIR and TEM.And the catalytic performance of prepared Ti modified catalyst for the steam reforming process of acetic acid was investigated on a fixed bed.The results show that the introduced Ti species enveloped the Ni particles and then formed the Niδ--Ov-Ti3+interface site through electron transfer during the reduction process.The formation of such interfacial sites on the support can optimize the reduction performance of the catalyst,improve the activity and stability of the catalyst in acetic acid reforming reaction,and enhance the ability of resisting metal sintering and coking.Under the conditions of S/C=3,WHSV=28.6 h-1,TOS=4 h,and 600 ℃,the Ni-Tis/ATP catalyst prepared with TiOSO4 as the titanium salt showed the most excellent performance in SRAA(steam reforming of acetic acid),with the acetic acid carbon conversion rate of 93.4%and hydrogen production rate of 77.6%.(2)Ni/Tis-ATP and Tis/Ni-ATP catalysts were prepared by step-by-step precipitation method,and compared with the co-precipitated Ni-Tis/ATP to study the effect of the precipitation sequence of Ti and Ni species on the performance of Ti-modified Ni/ATP catalysts.Use N2 adsorption-desorption,XRD,H2-TPR,XPS,NH3-TPD,TG,etc.to characterize/analyze the properties of the Ti modified catalyst,and then combined with its catalytic performance in the SRAA process,the structural evolution of the catalyst and the mechanism of hydrogen production from acetic acid were revealed.The results showed that different precipitation sequences formed different catalyst structures and greatly affected/regulated the performance of the catalysts.The flat Ni-Ti@ATP structure formed by co-precipitation endows the Ni-Tis/ATP catalyst with excellent reduction performance,surface acid sites and more Nδ--Ov-Ti3+ interface sites.The coupling/synergistic effect of Nio and Niδ--Ov-Ti3+interface site significantly improves the catalytic reforming performance of acetic acid for hydrogen production.(3)The Ni-TiR,Ni-Ti-ATPR and Ni-Ti/ATPR catalysts were prepared by the sol-gel method,and analyzed by XRD,H2-TPR and SEM characterization to explore the influence of the sol-gel method on the size of metal particles and catalytic performance.And the effect of reaction temperature on hydrogen production by steam reforming of acetic acid was investigated in a fixed bed reactor.The results show that the catalyst prepared by the common sol-gel method can form a strong and uniform interaction force,thereby better anchoring Ni species,reducing the size of metal particles,and providing more Ni-Ti interface and Ni reaction activity to participate in hydrogen production from acetic acid reforming.Among them,Ni-Ti-ATPR catalyst has the best performance,and the carbon conversion and H2 yield of acetic acid at 700℃ are 97.1%and 90.5%,respectively.Figure 31 table 9 reference 104...