Design And Preparation Of The Novel Porous Supported Molybdenum Sulfide-based Catalysts And Their Performance On Syngas Conversion To Higher Alcohols

As a highly abundant and renewable green resource,the development and utilization of biomass are of great significance for sustainable energy development and environmental protection.Preparing functional materials using biomass as raw material can reduce reliance on fossil fuels.Additionally,the diverse chemical structures and properties of biomass make it conducive to the construction of high-performance functional materials tailored to specific needs.In this paper,a series of biomass-based aerogels are developed and achieve excellent application results by designing and regulating their structures to optimize the heat and mass transfer occurring within them.First,thermal insulating alginate-based composite aerogels were synthesized by sol-gel and freeze-drying.They have a porosity of up to 92.40%and thus exhibit a thermal conductivity as low as 0.0314 W m^–1 K^–1.Nano calcium carbonate,serving as a flame-retardant filler and inducing ionic cross-linking,can promote the char formation of the cross-linked alginate network at high temperatures.In addition,the further introduction of boric acid crosslinking can synergistically improve the flame retardancy of aerogel.As a result,the limiting oxygen index of the alginate-based composite aerogels reaches up to 39.5%.The results of thermogravimetric analysis,thermogravimetry-infrared spectrometry,and in-situ diffuse reflectance infrared Fourier transform spectroscopy further confirmed a clear tendency of char formation of the alginate-based composite aerogels during thermal degradation.In addition,shells,pearls,and eggshells were adopted to substitute nano calcium carbonate for preparing all-natural composite aerogels,which also exhibited outstanding thermal insulation and flame-retardant properties.Subsequently,a semi-encapsulated structured chitosan-based composite aerogel was synthesized by two-step freeze-drying and applied to solar-driven interfacial evaporation.The hydrophobically modified chitosan aerogel serves as the core of the composite aerogel,enabling the composite aerogel to stably float on the water and isolating the evaporation interface from the bulk water.Its low thermal conductivity(0.0309 W m^–1 K^–1)prevents heat dissipation to the bulk water,effectively achieving thermal localization.The chitosan/carbon nanotube composite aerogel,possessing both photothermal characteristics（solar absorption of 90.7～94.4%）and hydrophilicity,serves as the outer layer and forms a two-dimensional water transport pathway.It can continuously transport water from the bulk water to the upper surface of the composite aerogel while absorbing sunlight and converting it into heat for in-situ water evaporation.The chitosan-based composite aerogel can achieve an evaporation rate of1.547 kg m^–2 h^–1 under 1 sun(1000 W m^–2),and it exhibits high stability in evaporating heavy metal wastewater and dye wastewater,producing clean water without pollutants.Next,the Janus structured cellulose-based composite aerogel was further developed with cellulose nanofibers（CNFs）as the basic framework and MXene（Ti₃C₂T_x）as the photothermal filler,and its solar-driven interfacial evaporation performance was investigated.The two parts of this cellulose-based composite aerogel have opposite wetting properties.The lower part is a hydrophilic CNF aerogel that can sustain continuous water transport,while the upper part is a hydrophobically modified CNF/MXene aerogel that can undergo photothermal conversion（solar absorption of94.2～97.9%）and has thermal insulation(axial thermal conductivity of 0.044 W m^–1 K^–1,radial thermal conductivity of 0.028 W m^–1 K^–1)properties.The two parts are combined into a whole through pre-freezing.Under 1 sun,the evaporation rate of this cellulose-based composite aerogel can reach 2.287 kg m^–2 h^–1.In addition,the unique Janus structure and the vertical microchannels inside the cellulose-based composite aerogel make it exhibit excellent salt resistance and durability during seawater desalination.Finally,chitosan-based composite moisture-absorbing aerogels with high porosity （up to 97.72%）and super hydrophilicity were synthesized.The chitosan-based aerogel obtained by freeze thawing and freeze-drying serves as the carrier and water reservoir for the hygroscopic salt and provides channels for water transport.Therefore,the continuously captured water vapor is stored inside the gel network.The prepared chitosan/polyvinyl alcohol@lithium chloride aerogel can absorb moisture up to 2.77 g g^–1 at 90%relative humidity.In a closed space with a volume of approximately 2200 times its own volume,it can reduce the relative humidity from90%to 32%within 2 h.Furthermore,compounded with photothermal nanomaterials,the chitosan/polyvinyl alcohol/carbon nanotube@lithium chloride aerogel can quickly desorb water under sunlight,thereby achieving energy-free cycling utilization.