| With the increasing consumption of fossil energy,there is a need to find new energy sources to replace the fossil energy,A feasible method has been proposed to prepare renewable gas,which is the catalytic pyrolysis process.Biomass is considered as the best alternative to fossil energy because it is a renewable energy source.Besides,an efficient method has been proposed to improve the utilization of biomass waste,which is a mixture of combustible gas and conducting the catalytic pyrolysis processes.Compared with biomass pyrolysis,the addition of waste plastics can not only increase the yield of pyrolysis gas,especially hydrogen,but also solve the environmental problem that plastics are difficult to degrade.Nickel-based catalysts are widely used because of their low cost and excellent performance.However,the problems of the nickel based catalyst are easy to inactivate and poison,which limit its large-scale development and application.In this paper,the stability of the catalysts was investigated by preparing and characterizing the catalysts.Our research has been studied and listed as follows:（1）Soybean straw and polyethylene（PE）were selected as the research objects.At the same time,the elemental analysis,industrial analysis and thermogravimetric analysis were carried out to evaluate the performance of the modified catalysts.The results showed that both soybean straw and PE had high volatile content,among which the volatile content of PE could reach 99.9%.The influence of mixing ratio of straw and plastic on pyrolysis products was also discussed.The results showed that the highest H2 yield was obtained when the mixing ratio was 5:5.（2）La Al O3carrier was prepared by sol-gel method,besides,Ni/La Al O3 catalyst was prepared by homogeneous precipitation method.then,the as-prepared samples were characterized by XRD,XRF,SEM,and BET.The characterization showed that the effects of reaction temperature,holding time,Ni loading and calcination temperature on the gas content were investigated as well.In the straw pyrolysis process,the highest H2concentration and yields was obtained,which were 43.1vol%and 238.5 m L/g,respectively.When the Ni loading is 10 wt%,the calcination temperature is 500℃,the reaction temperature is 800℃,and the holding time is 20 min.（3）The Ni/HC（honeycomb cinder）catalyst was prepared by the homogeneous precipitation method.The as-prepared samples were characterized by XRD,XRF,SEM and BET.The results exhibit that Ni O was uniformly attached to the surface of HC.The effects of reaction temperature,holding time,Ni loading and catalyst calcination temperature on the gas content were investigated.The highest H2 concentration reached 52.82 vol%,when the catalyst reaction temperature was 700℃,holding time was 20 min,Ni loading was 15 wt%,and calcination temperature was 400℃.The H2 concentration was still around 40 vol%after cycling experiments.（4）Al2O3-Ca O-Bamboo char（ACa B）and Al2O3-Ce O2-Bamboo char（ACe B）supports were prepared by the co-precipitation method.Ni/ACa B and Ni/ACe B catalysts were prepared by the homogeneous precipitation method.The performance of nickel based catalyst has been discussed by adjusting the molar ratio,mass ratio and La element loaded on the catalytic.At the same time,the performance of the catalytic was evaluated by pyrolysis of straw and the mixture matter of the straw and plastic at 700℃for 20 min.The results show that the performance of nickel-based catalyst prepared by molar ratio is better than that prepared by mass ratio.The H2 concentration of Ni/ACB catalyst reached 45.63vol%and 54.53 vol%,respectively.After 6 times cycling experiments,the H2 yield of Ni-La/ACB catalyst for catalytic pyrolysis of the straw and straw plastic mixture reached 33vol%and 34 vol%,respectively.In addition,the catalyst supported by ACa B was better than the catalyst supported by ACe B in terms of overall performance. |
