Light-driven Low-temperature Syngas Production From CH₃OH And H₂O Over Pt@SrTiO₃ Photothermal Catalyst

Converting the clean solar energy to chemical energy is a potential route to resolve the stubborn issues of energy crisis and environment pollution.Constructing high-efficient catalytic system is the core in this research field.In the field of the traditional photocatalysis,Most of the semiconductor photocatalysts can only absorb the ultraviolet and partial visible light in the solar spectrum,resulting in the low conversion efficiency of solar energy.Photothermal catalyst can convert the ultraviolet,visible and infrared light in the solar spectrum into thermal energy to driven thermo-catalysis,which is of significance to the efficient utilization of solar energy.The classic thermo-catalytic reactions are attempted to be realized via the photothermal catalysis;the development of efficient photothermal catalyst is the key issue.In this thesis,the Pt nanoparticles were loaded on strontium titanate?SrTiO₃,short for STO?support,which realized the photothermocatalytic reforming of methanol steaming.The main results and conclusions are as following.Firstly,the photodeposition and impregnation methods were adopted to prepare the samples with different supports and different loading amount of Pt.Various characterizations were used to study the phase,composition,morphology and photophysical properties of the samples.The as-prepared samples were evaluated the performance of methanol steaming reforming in a closed-circulated system.The reaction parameters,such as the loading amount of Pt and the ratio of water to alcohol,were optimized.Under a 2:1 ratio of water to alcohol,the sample with 3 wt%Pt loading via photodeposition?PD-3%Pt@STO?exhibited the highest activity.After 15min of irradiation,the conversion percentage of methanol reached 95.5%;the yield of syngas was 751.4?mol?H₂,465.4?mol;CO,286.0?mol?and meanwhile the selectivity exceeded 90%.Further cyclic tests indicated that the sample was relatively stable.The PD-3%Pt@STO sample could be heated up to 150 ^oC to drive the methanol steaming reforming;the operation temperature is close to the lowest temperature reported in the thermo-catalysis.Secondly,sol-gel alkali-dissolution-exothermal reaction was used to prepare nanoporous SrTiO₃ support of which specific surface area is 152.1 m²/g and narrow pore-size distribution is centered at 1.5 nm and 3.0 nm.The Pt nanoparticles was photodeposited over this support to prepare the PD-3%Pt@NP-STO sample that exhibited superior activity for photothermocatalytic methanol steaming reforming than the sample synthesized from the commercial SrTiO₃ support.The high performance of this sample can be attributed to that the more active sites were generated over the sample prepared via Pt loading over the support with large surface area and narrow pore-size distribution.This study achieved the photothermocatalytic methanol steaming reforming for the first time.The Pt loaded SrTiO₃ sample can drive this reaction under a low temperature of 150 ^oC and obtained good reactivity,stability,and selectivity.This work demonstrates that photothermal catalysis to realize traditional thermo-catalysis provides a new route for solar energy conversion.