Study On The Preparation And Performance Of Functional Materials That Can Catalyze The Transfer And Hydrogenation Of Biomass Oxygen-containing Compounds To Acid-base Functional Materials

Shifting from fossil-based resources to renewable biomass for the production of valuable chemicals and fuels is one of the significant aspects in sustainable chemistry for realizing the sustainable development of our society.Currently,many oxygen-containing organic molecules can be synthesized from lignocellulose via a series of catalytic transformations,and those oxygen-containing organic molecules can serve as feedstocks for the synthesis of liquid fuels and fine chemicals.Catalytic hydrogenations of oxygen-containing organic molecules act as one of key technologies in the manufacture of bio-fuels and fine chemicals.Nowadays,gaseous hydrogen is often used as hydrogen sources for hydrogenation reactions.However,the production of hydrogen in industrial mainly depends on the fossil-based resources.Besides,the cost of hydrogen storage and transportation is high;moreover,the highly flammable and explosive properties of hydrogen can bring about security risks in pratical production.Therefore,use of liquid hydrogen sources（e.g.,alcohols）to replace gaseous H₂ for the hydrogenation of biomass-derived molecules plays an important practical significance in the efficiently utilization of biomass.The selectivity hydrogenations of furfural（FF）,levulinic acid（LA）and its esters,both FF and LA（or its esters）are obtained from cellulose and hemicelluloses conversion,are studied in this paper.This paper focuses on design and preparation of heterogeneous catalysts and then developing them for the transfer hydrogenation of FF into FAOL,transfer hydrogenation-cyclization of ethyl levulinate（EL）intoγ-valerolactone（GVL）,and one-pot cascade conversion of FF/FAOL into GVL with using alcohol as hydrogen sources and solvent.Structure-activity relationships of heterogeneous catalysts,catalytic mechanisms and reusability of heterogeneous catalysts have also been studied in detail.Innovative results and main conclusions are listed in the following:（1）Ni²⁺-based catalysts（i.e.,NiO and NiFe₂O₄）,for the first time,were developed for catalytic transfer hydrogenation（CTH）of FF into FAOL with using2-propanol as hydrogen source.Various experimental parameters such as reaction temperation,reaction time,catalyst dosage and different alcohols as H-donor were investigated in detail.Kinetic studies and monitoring the distribution of products were done to speculate the possible reaction mechanism.The NiO and NiFe₂O₄ catalysts were proved reusable several times and maintained its pristine activity.Moreover,the remarkable catalytic activity of the NiO and NiFe₂O₄ catalysts were also observed in CTH of various other aldehydes,respectively.（2）A series of AlZr@Fe₃O₄ composite materials were prepared by precipitation-sedimentation method.Physico-chemical properties and structure of the as-prepared AlZr@Fe₃O₄ composite materials were systematacially characterized by various techniques.Those AlZr@Fe₃O₄ materials were developed as heterogeneous catalysts for the CTH of FF into FAOL with 2-propanol as H-donor.The best catalytic performance was observed for Al₇Zr₃@Fe₃O₄（1/1）among those as-prepared catalysts.Moreover,the magnetic properties of the Al₇Zr₃@Fe₃O₄（1/1）catalyst provided facile recovery using an external magnet after reaction.（3）NiO materials with urchin-like structure and flower-like structure were prepared by hydrothermal method,respectively;then developed for the CTH of FF into FAOL with alcohol as H-donor.Various reaction parameters,including reaction temperature,reaction time,different alcohols as H-donor and catalyst dosage,were studied in detail.It was discovered that NiO（P）-300 with urchin-like structure exhibited an excellent catalytic performance under mild reaction conditions（120°C and 3 h）.And the mechanism study was investigated via poisoning experiments.Moreover,the excellent catalytic performance of the sea urchin-like NiO（P）-300 was validated for gram-scale FAOL synthesis.Furthermore,the sea urchin-like NiO（P）-300 catalyst can be reusable for multiple reaction runs without significant activity loss and can maintain its pristine structure.（4）A series of Al-Zr mixed oxides with different molar ratios were prepared by co-precipitation method and utilized to catalyze conversion of EL to GVL with2-propanol as H-donor.It was found that Al-Zr mixed material exhibited the best catalytic activity when n（Al）/n（Zr）=7/3 and calcined at 300°C.Besides,the Al₇Zr₃-300 catalyst was able to be reused for several times with a slight loss in its catalytic activity with the assistance of calcinations in air.（5）A series of mesoporous acid-base bifunctional Zr/B mixed oxides with different molar ratios were prepared by a sol-gel method,and developed for conversion of EL to GVL by using alcohol as hydrogen source.It was found that Zr₁B₁（molar ratio of 1 to 1）showed superior catalytic performance to other as-prepared ZrB catalysts.Acid-base sites of Zr₁B₁ catalyst played a synergic role in synthesizing GVL from EL as evident by poisoning experiments.Additionally,a plausible reaction mechanism for hydrogenation-cyclization of EL into GVL was proposed.（6）A series of Zr doped mesoporous silicon dioxide（KIT-5）materials with Lewis-Br?nsted dual acidic sites were prepared by hydrothermal method,and various techniques were employed to characterize their physico-chemical properties and structure.Those Zr-KIT-5 materials were applied to catalyze the cascade conversion of FF into GVL in 2-propanol.When the molar ratio of Si to Zr was 10,the Zr-KIT-5catalyst（i.e.,Zr-KIT-5（10））exhibited the best catalytic activity.Based on the detected intermediates and byproducts via GC-MS analysis,a possible reaction pathway for the one-pot cascade conversion of FF into GVL was proposed.（7）Low-cost and easily available ZrOCl₂·8H₂O was for the first time exploited for catalyzing the cascade conversion of FF/FAOL into GVL in 2-propanol,giving63.3%and 52.1%yield of GVL,respectively.The collected solid after reaction calcined at 550°C in air could yield hollow microrods ZrO₂ material（i.e.,ZrO₂-（C））,which showed remarkable catalytic performance for the CTH of biomass-derived aldehydes or ketones.