Study On Carbonaceous Composite Catalysts For Decomposition Of Formic Acid To Hydrogen Near Room Temperature

Hydrogen has become a focus in the renewable field as a clean energy source with great development potential.Hydrogen storage materials have also become the object of intense research by research institutions.Formic acid is an organic product of metabolism,and its focus on the research of hydrogen storage materials is due to its good stability and green reproducibility.Compared to homogeneous catalyst,the synthesis method of heterogeneous catalysts are simple,easy to control and separate.The development of high-efficiency and low-cost multi-phase catalysts for decomposition of formic acid to hydrogen has become one of the research hotspots for hydrogen storage and release technology.Graphene has received much research attention because of its unique structure and good performance.In this paper,we take the carbon black?CB?,graphene oxide?GO?and strontium titanate?SrTiO₃?as the main subjects of research and prepared new efficient palladium-based,palladium-free new carbonaceous composite catalyst to hydrogen from formic acid at room temperature.Characterization methods were used to explore the relationship between multi-stage structure and catalytic performance of composite catalytic materials The main research results are as follows:1.The Pd₈Cu₂/N-CB composite catalyst prepared with APTMS grafted and modified N-based carbon black as supporter,which exhibited good catalytic performance and the hydrogen production rate reached 27.31 mmol g-1·h-1 and unit time transformation frequency?TOF?was 718.56 h-1 at 50 ?.The alloy consisted with Cu and Pd and its synergistic effect can enhance the activity.The N-based species present in PdaCu2/N-CB complexed with the alloy particles,made the alloy particles to be uniformly dispersed in a regular morphology and further enhanced the interaction between the nano-alloy particles and the support.The PdsCu2/N-CB catalyst has a relatively large specific surface area and can provide more active sites and increase catalytic activity.2.Bio-Pd/RGO-SrTiO₃ was synthesized by biomass reduction method using Gum Arabic as reducing agent and dispersant.The results showed that the Bio-Pd/RGO-SrTiO₃ catalyst has good catalytic activity on formic acid decomposition.At 50 ?,the hydrogen generation rate reached 17.56 mmol·g-1·h-1,which was about 2 times that of Chem-Pd/RGO-SrTiO₃ and the catalyst has good stability.The Pd nanoparticles prepared by the biomass reduction method have smaller particle size and better uniform dispersion than the chemical method.Bio-Pd/RGO-SrTiO₃ retained a certain amount of gum biomass residues on the surface of the catalyst and the interaction between residual groups and Pd nanoparticles restricted the growth of Pd particles.The noble metal Pd is present in the mixed valence state of Pd0,Pd2+,and Pd4+,which showed the better structural stability and faster electron transfer rate and improved the catalytic performance.3.A noble metal-free RGO/SrTiO₃ series catalyst were prepared by one-step solvothermal method.By adjusting the composite ratio of graphene oxide in the preparation process,the catalysts with different morphologies were obtained.Of these,6 wt%RGO/SrTiO₃ has the suerior activity.At 50 °C,the hydrogen production amount of 6 wt%RGO/SrTiO₃ reached 334.68 ?mol g-1 in 2 h.SrTiO₃ was strongly connected with graphene via Ti-C chemical bonds.The Ti-C bond created a channel for charge transportion between SrTiO₃ and RGO,which promoted the synergistic effect of RGO as the active center and successfully achieved the decomposition of formic acid.6 wt%RGO/SrTiO₃ has a graphene-coated special flower shape and relatively larger specific surface area,which was contributed to the improvement of activity.This provide a reference for the development of noble matal-free decomposition of formic acid at room temperature.