Research On Concentrated Solar Energy Driven Photothermal Catalytic Reforming Of Tar

The problem of tar in the process of biomass gasification not only reduces the efficiency of biomass gasification,but also corrodes and blocks the pipelines and equipment.Among many methods of tar treatment,catalytic reforming is a more effective method.In this way,tar is converted into combustible gas,which improves the biomass gasification efficiency.However,the reaction temperature is usually relatively high（approximately 700-900℃）and the catalyst also faces some problems such as carbon deposition and sintering deactivation.In order to solve this problem,the paper introduced sunlight to activate tar on the basis of thermal catalysis,used concentrated solar as source of light and heat to drive the catalytic reforming reaction,then developed a new catalyst with a photothermal synergistic catalytic effect to catalyze the reforming reaction proceeds to low temperature and high carbon conversion rate,which opened up a new way to deal with the problem of tar.The research contents of this article are as follows:In this paper,toluene was selected as the tar model compound.The experiments were carried out on the photothermal catalytic test bench.The catalyst used common thermal catalysts dolomite,Ni-γAl₂O₃,Ni-AC,CeO₂.It was found that Ni-γAl₂O₃ and Ni-AC had good carbon conversions of 78.48%and 81.76%at the temperatures of 600℃.However,the surface active component of the catalyst Ni was prone to agglomeration and sintering.According to the theoretical model of photothermal catalyst design,TiO₂,ZnO,CeO₂were used as the photocarrier and metal Ni as the active component.Three photothermal catalysts Ni-TiO₂,Ni-ZnO and Ni-CeO₂ were prepared by the dipping and the coprecipitation method.Toluene steam reforming experiment was carried out on the photothermal catalytic experiment bench.It was found that Ni-CeO₂ had a good effect of catalytic reforming and the conversion rate of toluene to carbon was as high as 91.8%at a low temperature of 600℃.Through independent reforming experiments on the active component Ni and the photocarrier CeO₂,their carbon conversion rate of independent experiments was 52.52%,which was much lower than the toluene-carbon conversion rate of Ni-CeO₂.It could be concluded that there was a strong synergy between the active component Ni and the photocarrier CeO₂.In order to verify the photothermal synergistic catalytic effect of Ni-CeO₂ and reveal its mechanism of action,the ultraviolet light with a wavelength of less than 420nm and a small part of visible light ware removed by the filter and the Remaining light drived toluene steam reforming experiments.It was found that the filtered carbon conversion rate was 82.2%,which was 9.6%lower than the full spectrum photothermal catalytic experiments.Because the active oxygen(O^2-)and hydroxyl groups generated after the CeO₂ surface was exposed to light were free activated substances such as radical（·OH）also activate toluene that is adsorbed on the surface of CeO₂,which promotes the occurrence of toluene catalytic reforming reaction.This verifies that there was a photothermal synergy between the active component of the Ni-CeO₂.In order to explore the best experimental working condition parameters of Ni-CeO₂,the experiment of toluene steam reforming was carried out by the reaction temperature,S/C,the ratio of the active component Ni and the carrier gas flow rate were used to perform toluene steam reforming on the photothermal catalytic experiment platform.Finally,considering the economic factors and others,the best experimental operating parameters of Ni-CeO₂ are:the reaction temperature is 600℃,S/C=3,active component Ni ratio is 10 wt%,Carrier gas flow rate is 100ml/min.At this condition,Ni-CeO₂ had the carbon conversion rate of 91.8%,synthesis gas output of 213.97 mmol/g and H₂/CO of 5.73.It had a high carbon conversion rate and high-quality synthesis gas.Under this working condition,the recycling performance of Ni-CeO₂ was investigated,and the results showed that Ni-CeO₂ had good resistance to carbon deposition and sintering.After 8 times cycles of experiments,the carbon conversion rate only decreased by 1.6%.