Hydrogen-rich Syngas Production By Pyrolysis Of Wet Sewage Sludge And Straw

Biomass is a renewable resource.Biomass pyrolysis/gasification is one of the most effective ways to convert biomass into fuel.The main problem with pyrolysis is the presence of a large amount of tar in the gas.Catalytic cracking has high cracking tar efficiency and gas reforming ability,and is considered as a technically feasible and economical gas purification technology.In this paper,a series of catalysts were prepared by the deposition precipitation method and used for the co-pyrolysis of wet sludge and wheat straw to produce hydrogen-rich syngas.The main research contents and conclusions are as follows:(1)The NiO/ZrO₂ catalyst was prepared using Zr-metal organic framework(Zr-MOF)as support under air atmosphere at 600?.A series of experiments were performed to explore the effects of reactor temperature,straw content and Ni loading on the content of syngas.The experiments demonstrated that the mesoporous Zr-MOF support particles were octahedral,with a specific surface area of 805.93 m²/g and an average pore diameter of 20.14nm.The NiO/ZrO₂ catalyst had high thermal stability and catalytic activity.Compared with non-catalyst biomass pyrolysis,the H₂ yield increased significantly from 0.39 mol/kg to12.65 mol/kg by using NiO/ZrO₂ catalyst at 500?.(2)The Ni/Zr-MOF catalyst was prepared using Zr-MOF material as support under nitrogen atmosphere at 500?.A series of experiments were performed to explore the effects of the Ni/Zr-MOF catalyst,Ni loading,catalyst recycling and egeneration performance on the content of syngas.The experiments demonstrated that nickel was uniformly dispersed on the surface of the catalyst,and the Ni/Zr-MOF catalyst maintained an octahedral morphology.Compared with non-catalyst biomass pyrolysis,the H₂ yield increased from0.39 mol/kg to 11.87 mol/kg using the Ni/Zr-MOF catalyst at 500°C.After 10 instances of reuse,the H₂ yield was still as high as 10.11 mol/kg.(3)The Ni/CSC,Ni-Fe/CSC and Ni-Fe-La/CSC catalysts were prepared using corn stalk char(CSC)as support under nitrogen atmosphere at 900?.A series of experiments were performed to explore the effects of reactor temperature,catalyst type,moisture content of wet sludge and catalyst recycling on the composition and yield of gasification gases.The experiments demonstrated that the char-supported catalysts had abundant pore structures and surface functional groups.The Ni-Fe-La/CSC catalyst showed much higher hydrogen production compared with the Ni/CSC and Ni-Fe/CSC catalysts.Compared with non-catalyst biomass pyrolysis,the H₂ yield increased from 4.53 mol/kg to 11.96 mol/kg using Ni-Fe-La/CSC catalyst at 600°C.(4)The effect of lanthanum content on Ni-Fe-La/CSC catalyst was studied.The experiments demonstrated that the active component in Ni-Fe-La/CSC catalyst was nickel-iron alloy(Fe_0.64Ni_0.36).La₂O₃ could reduce the carbon deposition on the catalyst,improve the thermal stability of the catalyst,increase the dispersion of nickel-iron alloy on the surface of the support,and reduce the grain size of the nickel-iron alloy.The optimum addition amount of lanthanum is 8 wt%.The H₂ contents were,respectively,37.83 vol%and 33.16vol%after the Ni-Fe-8%La/CSC catalyst was used one and ten times,only reducing by4.67%,with a long cycle life.