Preparation Of Carbon-based Non-noble Metal Catalysts And Their Catalytic Activity For Directional Conversion In Furfural (Derivatives)

With the continuous depletion of fossil resources,the use of biomass or its derivatives as renewable carbon resources for the preparation of bulk industrial chemicals has become a very active research field.Furfural(derivative)is one of the most attractive biomass-derived platform molecules in recent years,which can be prepared from biomass such as hemicellulose or cellulose.Cellulose and hemicellulose are the most abundant and cheapest biomass resources on the earth,and the synthesis process of furfural is very mature at present.Therefore,the process development of furfural(derivatives)high value-added downstream products is undoubtedly of great significance for social,economic and environmental.Catalytic hydrogenation based on metal catalysts is an important method for the conversion of furfural(derivatives).however,the existence of multiple active groups in the molecular structure of furfural(derivatives)has brought great difficulties to the design of catalysts in the study of directional conversion.In view of the high cost of precious metal catalysts,low activity and poor stability of cheap metal catalysts in the directional conversion of furfural,there are many problems.In this study,the synthesis of 2-methylfuran and?-valerolactone as an example,try to design new carbon-based cheap metal catalysts,and with the help of catalyst characterization technology more systematic study of the catalyst structure-activity relationship and mechanism.The main contents of this paper are as follows:1.Taking the directional conversion of furfural to 2-methylfuran as an example,a microwave-assisted reduction-ammoniae vaporation synergistic catalyst preparation strategy was designed,and a nitrogen-doped graphene-supported Cu-Cu₂O(Cu-Cu₂O/N-RGO)bifunctional catalyst with high activity and high stability was constructed.The yield of 2-methylfuran was 95.5%under the optimum reaction conditions(hydrogen pressure 1.5 MPa,reaction temperature 240?and reaction time 3 h).and the catalyst was reused for 5 times without obvious change in catalytic performance.The characterization results show that the better activity of the catalysts can be attributed to the synergistic catalysis of Cu ⁰and Cu₂O,and the better stability of the catalysts is mainly due to the strong interaction between metal sites and support.2.Take that directional conversion of ethyl levulinate to?-valerolactone as an example,nitrogen-doped carbon/cobalt(Co@NC)composites were successfully prepared by hydrothermal chelation and pyrolysis.The existence form of cobalt particles in the catalyst was changed by adjusting the pyrolysis temperature to achieve the best synergistic effect of Co⁰and Co₃O₄nanoparticles in the catalyst.Ethyl levulinate was converted to?-valerolactone in 98.0%yield by one-pot method under the optimum reaction conditions(hydrogen pressure 2.0 MPa,reaction temperature 200?and reaction time 3 h).The catalyst can be rapidly separated from the reaction mixture by external magnetic field and reused for 10 times without obvious change in catalytic effect.The characterization results confirmed that the excellent catalytic performance of the catalyst was due to the synergistic effect of Co⁰and Co₃O₄.3.Take that directional conversion of levulinic acid to?-valerolactone as an example,In view of the strong corrosiveness of levulinic acid to the catalyst in aqueous solution,the encapsulated nitrogen-doped carbon nanotube confined cobalt-based catalyst(Co@NCNT)was successfully prepared.The results showed that the yield of levulinic acid to?-valerolactone catalyzed by Co@NCNT was 100%under the optimum conditions(hydrogen pressure 2.0 MPa,reaction temperature 180?and reaction time 3 h).The catalyst is reused for 5 times without obvious change,and the disadvantage of poor durability of non-noble metal catalyst in acidic medium is overcome.