Mechanism Of Thermal Effect On Bio-glycerol Photothermal Reforming Hydrogen Production

Conversion of biomass derivatives driven by solar energy into clean energy carriers is an effective method for renewable energy production and waste treatment.During this process,establishing efficient catalysts to convert bio-hydrocarbons for renewable hydrogen is essential.However,the current understanding of the thermal effects of hydrogen production is limited due to the difficulty in separating the light and thermal radiation of solar energy.In order to realize the efficient conversion of solar energy to hydrogen energy,this thesis focuses on the photothermal reforming hydrogen production performance of semiconductor silver and gold nanoparticle loaded TiO₂ photothermal catalyst in aqueous bio-glycerol solution and the construction of solar absorption enhancement unit.This study consists of the following contents:（1）Study on the effect of temperature on the photothermal glycerol reforming of Ag/TiO₂nanosheet catalyst for hydrogen productionThe amount of silver loading determines the strength of the photothermal effect,a series of TiO₂ nanoflakes loaded with different weight ratio of silver（Ag）nanoparticles photothermal catalysts were experimentally investigated.By loading 1-9 wt.%Ag nanoparticles on TiO₂ nanoflakes（TNF）,the localized surface plasmon resonance（LSPR）effect of Ag significantly increased the equilibrium temperature,and a dynamic equilibrium between LSPR and thermal dissipation was found,with a maximum temperature rise of 21.1℃for the solution（7 wt.%loading）.Increasing the silver loading mass ratio increases the equilibrium temperature,but at the same time the reforming hydrogen production performance decreases,with the highest reforming performance being 880μmol/g at 1 wt.%loading.（2）Photothermal synergistic effect of Au/TiO₂ nanosheets reforming glycerol for hydrogen productionIn order to further investigate the thermal effect of plasmonic co-catalyst on photothermal reforming hydrogen production,TiO₂ nanosheets loaded with gold（Au）nanoparticles were prepared as a photothermal catalyst for the photothermal reforming of bio-glycerol.The DRIFTS and in-situ EPR results showed that the generation of photogenerated carriers was the key to the photothermal reforming of bio-glycerol.The hot carriers excited by Au nanoparticles participated in the hydrogen production reaction neither by direct nor indirect transfer,but promoted intermolecular collisions between reactants through thermalization,and their derived local thermal effects could improve the migration efficiency of photogenerated carriers and act as a special reaction site for the intermediates The photo-thermal enhanced reforming of the iso-excited elements of Au/TiO₂ catalyst can increase the hydrogen yield by58%,while the hydrogen generation and adsorption equilibrium constants are 2.38 mmol.g^-1·h^-1 and 7.00 m L.mmol^-1,respectively.The mass transfer kinetic model calculations demonstrate that this thermal effect is more inclined to promote the adsorption and desorption of chemical species rather than chemical bond activation.（3）Preferential selection of photothermal catalysts and the efficient photothermal conversion for hydrogen production in composite catalytic unitsIn order to improve the conversion efficiency,light absorption capacity and catalyst stability of infrared thermal radiation in the photothermal conversion process,The new multifunctional Au/TiO₂@MPCM with core-shell structure was designed and synthesized by wet chemical reduction and electrostatic adsorption self-assembly methods to convert the solar energy and to enhance the stability of suspension for the purpose of improving the performance of photothermal reforming for hydrogen production.The experimental results showed that the microencapsulation of Au/TiO₂ photothermal catalyst could provide an effective reaction area and good dispersion stability,and the hydrogen production rate and LTH efficiency were improved by 43%and 0.3%,respectively.The photothermal conversion efficiency and specific absorption rate of the composite structure were calculated to be 25.01%and 277%higher than those of the Au/TiO₂ suspension,respectively.The proposed microencapsulated catalytic hydrogen production and thermal storage method is a guideline for improving the full-spectrum solar energy conversion efficiency.In summary,it is confirmed that the thermal effect of plasmon is an effective method to enhance the overall hydrogen production performance of bio-glycerol reforming,and it is also confirmed that the constructed Au/TiO₂@MPCM is an effective means to efficiently convert solar energy absorption into thermal and chemical energy,which is beneficial to improve the solar energy utilization efficiency.