Preparation Of Hydrotalcite-derived Acid-base Catalyst And Their Application In Catalytic Conversion Of Furfural

Biomass,as the only renewable organic carbon source on the earth,promotes its efficient transformation and utilization is an effective technical way and important task to realize the"carbon peaking and carbon neutrality"goals,which fits the energy development strategy of our country.Among many biomass derivatives,furfural（FF）is a kind of lignocellulosic derivative,which is produced by the catalytic hydrolysis of agricultural waste biomass by acid.It has a wide range of sources,simple preparation,and low price.It can prepare a variety of high-value-added chemicals through a specific catalytic process and has great potential to further replace some fossil energy products.Furfural is a typical C5 biomass-based furan compound with a short carbon chain and more unsaturated functional groups.It can be used to synthesize fuel precursors and chemicals with high added value through carbon chain extension reaction and hydrogenation reaction.Among them,furfural and some carbonyl compounds containingα-H can be obtained by aldol condensation reaction under the action of a solid acid-base catalyst through various long-chain fuel precursors.In addition,the widely used furfuryl alcohol（FOL）can be obtained by using solid acid-base catalyst to reduce the C=O bond in FF by using alcohol compounds as hydrogen source and hydrogen transfer reaction without using the high-pressure hydrogen.However,FF contains a variety of active functional groups,which brings great challenges to the synthesis of specific target products.In this paper,a series of hydrotalcite composite oxides were synthesized by optimizing the types and proportions of elements and changing the calcination temperature.As a solid acid-base catalyst,furfuryl acetone was synthesized by furfuryl acetal condensation,and furfuryl alcohol was synthesized by catalytic transfer hydrogenation of furfural.The research contents are as follows:1.Mg-Al composite oxide was used in furfural and acetone hydroxyl aldehyde condensation preparation furfuryl acetone.The precursor of Mg Al-LDHs was synthesized by hydrothermal method,and a series of Mg-Al composite oxides were synthesized by changing the calcination temperature.Mg₃Al₁-LDO showed excellent catalytic activity at 300℃.Under the optimal reaction conditions（120℃,2 h）,the conversion rate of furfural was 99%,and the yield of FAc was 96.5%,showing excellent cyclic stability.The catalyst was reactivated by calcination,and the catalytic activity remained unchanged for 6 cycles.Based on the structural characterization,Mg₃Al₁-LDO（300℃）has a high specific surface area and can provide abundant Br（?）nsted basic site（OH^-）and Lewis acid-base center(Mⁿ⁺-O^2-),which can optimize the adsorption and mass transfer of reactants,promote the formation of carbonation,so as to improve the catalytic performance of aldol condensation.2.The preparation of furfuryl alcohol by catalytic transfer hydrogenation of furfural by cobalt-based composite oxides.The Co-precipitation method was used to prepare Co Mg Al-LDHs as the precursor.A series of Co-based composite oxide catalysts were obtained by changing the molar ratio of elements and calcination temperature.Isopropyl alcohol was used as the hydrogen source to achieve the selective synthesis of furfuryl alcohol by catalytic transfer hydrogenation of furfural.Compared with other catalysts,Co_1.5Mg_1.5Al₁-LDO（500℃）showed the best reactivity at 500℃.The conversion rate of furfural is 97.5%and the selectivity of furfuryl alcohol is 95.7%at 160℃and 6 h.Combined with various characterization methods,it can be seen that the introduction of Co species optimizes the Lewis acid-base properties of the catalyst,promote the formation of hydrogen species and the selective activation of the C=O bond,and thus improve the catalytic transfer hydrogenation performance.The catalyst maintained good cyclic stability and showed excellent catalytic activity and selectivity for other biomass-based carbonyl compounds.