Catalytic Conversion Of Cellulose And Its Platform Ethanol On Mixed Metal Oxides Supported Nano-Ni

As the only renewable carbon resource in nature,the conversion of biomass,especially the most abundant cellulose,into clean energy,fuels,and chemicals has attracted arising attention.But the diverse chemical bonds in cellulose and its platform molecules,such as O-H bonds,C-H bonds,C-C bonds,and C-O bonds,make it difficult to control the reaction orientation.In this dissertation,the synergistical catalysis between Ni nanoparticles and basic sites or acidic-basic sites was proposed for controllable activation of chemical bonds in cellulose and its platform molecules.And multifunctional mixed metallic oxides supported Ni nanoparticles were designed based on the adjustable compositions and the lattice confinement effect of laminates of layered double hydroxide(LDHs).The specific research is as follows:1.The hydrogen production from aqueous phase reforming of cellulose suffers the difficulty in simultaneous activation of O-H,C-H,and C-H bonds,resulting in low hydrogen production efficiancy.To solve this challenge:1)A synergistical catalysis between Ni nanoparticles and MgAl-layered double oxides(MgAl-LDO)was creatively proposed,where the basic sites on MgAl-LDO activate the O-H bonds thus facilitating the cleavage of C-H and C-C bonds on Ni nanoparticles.Up to 30.9%of hydrogen yield was achieved via modulating the density of basic sites and the Ni-LDO interfacial interactions,higher than the best hydrogen yield reported in the references.2)The competition and dependency of the cleavage of C-H/O-H bonds and C-C bonds on the surface of Ni particles with varied particle sizes were revealed by regulating Ni particle size.It was found that with decreasing Ni particle size,the ability to cleavate C-H bonds became strongger while the C-C bond weaker.As a sequence,the catalyst deactivated easily due to carbon deposition.The methanation on larger Ni particles became strongger,resulting in higher selectivity to methane.3)The abundant interfacial sites and strong interfacial interactions between Ni particles and MgAl-LDO could not only promote the water gas shift reaction while inhibit the methanation,but also supress the Ni particle aggregation,thus enhancing the reusability.4)Up to 70%of hydrogen yield has been obtained by regulating the surface defects not only on the support but also Ni nanoparticles by controlling the nuleation condition of the precursors.The Mg vacancies faciliate the C-H bond cleavage and the defects on Ni particles boost the cleavage of C-H and C-C bonds.Almost no decrease in hydrogen yield was detected in tenth run,demonstrating good regeneration and reusability.2.For valorization of ethanol molecules,a strategy of simultaneous formation of C-C and C-N bonds via activation of O-H bond and C-H bonds in ethanol,double cross condensation,and hydrogen transfer has been creatively proposed,affording 1,2,3,4-tetrahydroquinoline(THQ)and its derivatives:1)A heterogeneous synergistical catalysis between acidic-basic sites on NiAl-LDO and nano-Ni was designed,affording THQ with a yield of 97%without the addition of liquor base or external hydrogen.Ethanol dehydrogenation was found to be the rate-determining step.The NiAl-LDO supported nano-Ni shows good substrate tolerability,affording a variety of THQ derivatives with high yield.2)The dependence on the nano size of the Ni particles has been revealed.With decreasing Ni particle size from 5.0 to 3.0 nm,ethanol dehydrogenation shows a dramatic increase.The quasi-in-situ XPS and FTIR of ethanol adsorption revealed the nature of the size effect of Ni particles to be Ni0-Niδ+synergistical catalysis,where Niδ+ sites activate O-H bonds in ethanol while Ni0 sites cleave the α-C-H bonds in ethoxyl.Pre-activation of the Ni surface effectively increased the population of surface Niδ+ sites,accelerating the Ni0-Niδ+ synergistic catalysis.3)The L acidic properties of the catalyst have been modulated via tuning the composition of LDHs precursors.Increasing the amount of L acid sites facilitates the double cross condensation,thus promoting the selectivity to THQ.Introducing Zr to the support not only increases the amount of L acid sites but also the strength of the L acid sites,facilitating the second double cross condensation,affording N-ethyl-THQ with a yield of 95%.The NiAlZr-LDO supported nano Ni shows good substrates tolerability,affording a variety of N-ethyl-THQ derivatives with high yield.More meaningfully,N-ethyl-6-[3-(1-piperidinyl)propoxy]-THQ,an effective H3 receptor antagonist,was obtained with a yield of 87%.