The Preparation Of Novel Biobased Heterogeneous Br(?)nsted Acid Catalysts And Their Application On The Synthesis Of Liquid Biofuel 5-ethoxymethylfurfural

With the aggravation of the energy crisis and deterioration of ecological environment,accelerating the development of clean and renewable alternative energy has become the focus of scientific research.5-ethoxymethylfurfural?EMF?is a potential liquid biofuel or fuel additive with high energy density.It is mainly prepared by hydrolysis and etherification of carbohydrate biomass in the ethanol system in an acidic environment.Therefore,the development of low-cost and efficient acid catalysts has become a key issue.However,although the traditional homogeneous acid catalyst has better catalytic effect,it is difficult to separate and recover and the corrosion of equipment and other problems have seriously limited its applicability.It is important to develop heterogeneous solid acid catalyst,which is easy to separate,environmental protection and high efficiency.The heterogeneous solid acid catalysts currently developed for the synthesis of EMF generally have the disadvantages of high cost,low stability,and difficulty in realizing large-scale industrial production.Therefore,it is of great significance to select low-cost crude waste biomass to prepare bio-based heterogeneous solid acid catalyst with high activity,high stability and easier separation,and then to efficiently synthesize economic and environmentally friendly liquid biofuel?EMF?.In this paper,a series of high quality biomass based heterogeneous solid Br???nsted acid catalysts with high stability,high activity and simple separation operation were successfully prepared by simple hydrothermal carbonization technology using crude biomass waste camellia oleifera shells as the main raw material.And it showed excellent performance in the synthesis of green renewable liquid biofuel EMF,which greatly reduced the production cost and provided new ideas for industrial production.The details are as follows:1.A biobased heterogeneous solid Br???nsted acid catalyst ACMSs-350-SO₃H-12.5with aromatic carbon microspheres was successfully fabricated from waste camellia oleifera shells by simple hydrothermal carbonization-annealing-sulfonation process.Then,the heterogeneous solid Br???nsted acid catalyst was used to catalyze the synthesis of green renewable liquid biofuel EMF from fructose.350 ^oC low temperature annealing process helps to increase the activity of the catalyst due to the simultaneous maintenance of the spherical microstructure and aromatic carbon framework.The biobased heterogeneous solid Br???nsted acid catalyst prepared by using low temperature annealing carbon microspheres exhibits relatively high catalytic activity because of its abundant surface-SO₃H and uniformly dispersed spherical microstructures.In the catalytic reaction,the proper fructose concentration is favorable for the formation of EMF,and the optimal fructose dosage is 0.5 mmol.In addition,the asprepared catalysts exhibit considerably high stability in the current EMF synthesis system,and they can maintain a similar level of reactivity after four catalytic cycles.2.A highly active biobased heterogeneous solid Br???nsted acid catalyst M-CMSs-SO₃H was prepared by hydrothermal carbonization with the aid of p-methoxyphenol and sulfonation under infrared light.The biomass based heterogeneous solid Br???nsted acid catalyst showed good acid catalytic activity in the synthesis of EMF from fructose,and the EMF yield was over 60%in a short time.The sulfonation reaction was carried out under infrared light irradiation to achieve an efficient loading of the acidic functional group-SO₃H,and the optimum sulfonation time was 8 hours.The addition of p-methoxyphenol promoted the formation of carbon microspheres,greatly increasing the loading of the active group-SO₃H,and the optimum dosage of p-methoxyphenol was 1.8 g.3.In view of the fact that most heterogeneous solid acid catalyst separation procedures are currently complicated,they are not suitable for industrial production applications,therefore,we successfully prepared an"integrated"heterogeneous solid Br???nsted acid catalyst PTFE@ACMS-SO₃H by a simple hydrothermal carbonization-low temperatureannealing-roomtemperaturesulfonationprocesswith polytetrafluoroethylene fiber and waste camellia oleifera shells as raw materials and Phloroglucinol as auxiliary agent.It was applied to the reaction of5-hydroxymethylfurfural?HMF?to 5-ethoxymethylfurfural?EMF?in an ethanol system,and in a short period of time,the EMF yield is over 60%,and the HMF conversion rate is over 90%.The catalyst has the advantages of simple separation operation,high activity and high stability.The material is sulfonated at room temperature to effect loading of the acidic functional group-SO₃H.The low temperature annealing process significantly improved the acid catalytic activity and stability of the catalyst.The optimum annealing temperature and time were 320 ^oC for 2 hours.The catalyst separation operation is simple,the stability is strong,and the activity is maintained even after repeated use for 3 times.