Studies On Producing Nitrogen-containing Chemicals Via Thermo-Catalytic Conversion And Ammonization Of Biomass

At present,China’s primary energy consumption is dominated by coal.The large consumption of fossil energy causes serious environmental pollution problems.The continuous development of energy demand and efficient use of energy have presented great challenges to the scientific and rational development of energy research.Promoting diversification of energy structure and increasing energy supply have become one of the inevitable trends in the development of the energy sector.As a new energy source in the world,it plays an important role in coping with global climate change,energy supply and environmental protection.Biomass is the only renewable carbon source that can be converted into a variety of fuels and chemicals and has attracted widespread attention.At present,thermo-catalytic conversion and ammonization is an economically method for converting biomass to nitrogen-containing chemicals.Indoles,pyrroles and acetonitrile are high value-added nitrogen-containing chemicals.They have a stable market and a bright prospect in medicine,pesticides,food,chemical industry and other fields.However,there are still many problems in the preparation process of nitrogen-containing chemicals,such as serious pollution,harsh reaction condition,low target yield and complex catalytic system.Based on these problems,we have developed a variety of catalytic systems in the thermo-catalytic conversion and ammonization of biomass feedstock.With the optimal reaction parameters,a targeted and efficient preparation process for various nitrogen-containig,chemicals was achieved.The paper is divided into the following sections:In the first chapter,the lignocellulosic biomass and microalgae were briefly introduced,followed by a detailed review of current developments in the thermo-chemical conversion of biomass and recent advances in the field of thermo-catalytic conversion and amination.At the same time,the main uses and preparation processes of various high value-added nitrogen-containing chemicals were introduced.In the second chapter,furfural,an abundant biomass derived compound,was converted into indoles via thermo-catalytic conversion and ammonization with zeolites.The effects of reaction temperature,catalyst,weight hourly space velocity and ammonia to furfural molar ratio on the yield and selectivity of indoles were investigated systematically.The HZSM-5 catalyst was recycled for five times and showed slight deactivation.Three possible aldehyde group of furfural conversionpathways were proposed and one possible reaction pathway from furfural to indoles was verified based on the experimental and quantum calculation results.In the third chapter,we present the effect of the introduction of nitrogen into ammonia atmosphere in the thermo-catalytic conversion process of furfural to indoles.The introduction of N2 into NH3 significantly enhanced the indoles production and catalyst stability at lower temperature.Using furan derivatives as the feedstock,diluted NH3 also showed a positive effect on the production of N-containing chemicals.Functional groups in the furan derivatives strongly affect the product distribution.It was found that the increase of indoles production from furfural was because the generation of 2-furonitrile via the side reaction pathway to form coke was inhibited by the dilution of NH3.The catalysts were tested via five reaction/regeneration cycles in pure and diluted NH3 atmosphere and characterized by N2 adsorption/desorption,XRD,XRF,NH3-TPD analyses and SEM.Compared in pure NH3,the catalysts in N2 diluted NH3 was more stable,which could be due to the lower degree of dealumination,structure damage,and acid site loss.In the fourth chapter,cellulose was selectively converted into pyrroles via catalytic fast pyrolysis under ammonia atmosphere over the catalyst.Both in situ and ex situ lab-scale fast pyrolysis sets were designed and used for investigation,and more pyrroles were produced via in situ catalytic fast pyrolysis process.The reaction apparatus,catalyst and catalyst-to-cellulose ratio on the product distribution were investigated systematically.The possible conversion pathway of pyrroles via catalytic fast pyrolysis cellulose under ammonia atmosphere and low temperature condition was proposed.In the fifth chapter,we reported a new route of conversion of acetonitrile via catalytic fast pyrolysis of low-lipid microalgae under ammonia atmosphere.A catalyst of 2%Ga supported on HZSM-5 with Si/Al of 25[2%Ga/HZSM-5(25)]was prepared.Using Chlorella vulgais as a raw material,acetonitrile was prepared with high selectivity over this catalyst.The conversion pathways of the three major components(carbohydrates,proteins and lipids)in microalgae through thermo-catalytic conversion and ammonization were investigated.Expanded a variety of low-lipid microalgae and lignocellulosic biomass as raw materials for acetonitrile production,providing a new idea for the efficient use of biomass resources.In the fifth chapter,we summarize and look forward to the full text.In summary,this paper focused on the thermo-catalyitc conversion and ammonization of biomass-based platform molecules and biomass into nitrogen-containing chemicals through different catalytic systems.The effect of catalysts and reaction conditions on the target product was explored.This is a new approach to the efficient and high-value utilization of biomass resources.