Effect of surface properties of TiO2 on the performance of Pt/TiO2 catalysts for furfural hydrogenation

Strong metal-support interactions of TiO2 interface-loaded Pt constructed under different atmospheres for adjusting the hydrogen storage reaction performance of N-ethylcarbazole

In this study, two series of samples (rT-Pt/TiO2 prepared with a hydrogen pretreatment and Tr-Pt/TiO2 prepared with an oxygen pretreatment) were prepared by treating commercial TiO2 supports in different atmospheres to establish different TiO2 interfacial structures, followed by the addition of platinum nanoparticles (NPs) for the catalyzed hydrogenation/dehydrogenation cycle of N-ethylcarbazole (NEC). The kinetic analysis and reaction mechanism were investigated by combining XRD, Raman, CO-DRIFT, HRTEM, XPS, H2-TPD and DFT calculations. It was found that the performance of the samples for the NEC system's cyclic hydrogen storage could be modulated by treating the TiO2 interfacial structure with different atmospheres varying the extent of strong metal-support interaction (SMSI). In addition, a turnover frequency (TOF) of 191.52 min-1 for dehydrogenation was achieved at 170 °C, which is better than the previously reported catalysts. Experimental studies (characterization and kinetic studies) and DFT calculations confirmed that the SMSI of the Tr-Pt/TiO2 series samples promoted the escape of H2 and enhanced the catalytic activity for 4H-NEC in the 12H-NEC dehydrogenation reaction. In the NEC hydrogenation reaction, the rT-Pt/TiO2 series samples were pretreated with H2 before loading platinum metal, which led to the early activation of Ti4+ in their carriers, and thus suppressed the SMSI effect of the reduction process after loading platinum. This process caused the interface formed by rT-Pt/TiO2 to have a higher energy barrier to 6H-NEC, which is an intermediate product of the NEC hydrogenation process, and this interrupted the hydrogenation process of 6H-NEC.

Promoter Effect of Pt on Zr Catalysts to Increase the Conversion of Furfural to γ-Valerolactone Using Batch and Continuous Flow Reactors: Influence of the Way of the Incorporation of the Pt Sites

The valorization of biomass and its transformation into fuels are highly interesting due to the abundance of biomass and its almost neutral carbon emissions. In this article, we show the production of γ-valerolactone (GVL), a valuable product, from furfural (FF), a compound that can be easily obtained from biomass. This FF to GVL transformation involves a catalytic cascade reaction with two hydrogenation steps. Pt and/or Zr supported on sepiolite catalysts have been prepared and tested in the FF transformation reaction. A physical mixture of a Zr-based and a Pt-based catalyst has reached a yield to GVL of ca. 50% after 16 h at 180 °C. This performance largely exceeds that obtained by each of the single Pt or single Zr metal catalysts independently, showing a strong synergistic effect. These data suggest that each metal (Pt and Zr) plays an important and complementary role in different reaction steps. Furthermore, the physical mixture appears to be much more efficient than bimetallic Pt/Zr catalysts synthesized with the same amount of metals. The role of the type of acidity and the oxidation state of the surface platinum species on the catalytic performance has been discussed. Moreover, this reaction has been carried out in batch and continuous flow reactors, and a comparative study between the two operation modes has been undertaken. A certain correlation between the catalytic results obtained by both operation modes has been found.

A Comprehensive Review on Metal Catalysts for the Production of Cyclopentanone Derivatives from Furfural and HMF

The catalytic transformation of biomass-based furan compounds (furfural and HMF) for the synthesis of organic chemicals is one of the important ways to utilize renewable biomass resources. Among the numerous high-value products, cyclopentanone derivatives are a kind of valuable compound obtained by the hydrogenation rearrangement of furfural and HMF in the aqueous phase of metal-hydrogen catalysis. Following the vast application of cyclopentanone derivatives, this reaction has attracted wide attention since its discovery, and a large number of catalytic systems have been reported to be effective in this transformation. Among them, the design and synthesis of metal catalysts are at the core of the reaction. This review briefly introduces the application of cyclopentanone derivatives, the transformation mechanism, and the pathway of biomass-based furan compounds for the synthesis of cyclopentanone derivatives. The important progress of metal catalysts in the reaction since the first report in 2012 up to now is emphasized, the characteristics and catalytic performance of different metal catalysts are introduced, and the critical role of metal catalysts in the reaction is discussed. Finally, the future development of this transformation process was prospected.

Selective aqueous-phase hydrogenation of furfural to cyclopentanol over Ni-based CNT catalysts

AbstractCyclopentanol (CPL) was an eco-friendly solvent as well as important platform chemical which could be generated from biomass-derived furfural (FFA). In this paper, A series of Ni, Cu, Mo, Co bimetallic catalysts with different metals loadings supported on Carbon nanotubes (CNT) were synthesized by an impregnation method for aqueous-phase hydrogenation of FFA to obtain CPL. Various effects of reaction parameters such as, reaction solvent, reaction temperature, reaction time, and different loading amount of Ni over bimetallic Ni-based CNT catalysts were fully investigated. Among the catalysts studied, (15 + 5) wt% NiCu/CNT catalysts showed high conversion of FFA and 88% selectivity towards CPL in water and 96% selectivity towards acetal in methanol at mild condition of 160℃, 2 MPa hydrogen and 4 h reaction time. NiCu bimetallic synergistic effect was interpreted through H₂-TPR and NH₃-TPD measurement and a possible pathway was proposed. The features of the CNT supported catalysts were investigated via XRD, XPS, TEM, H₂-TPR and NH₃-TPD. The Ni and bimetallic NiCu catalysts synthesized in this work were inexpensive and simple, which made them a promising candidate for the conversion of biomass-derived FFA to CPL.

Crystal-Plane-Dependent Guaiacol Hydrodeoxygenation Performance of Au on Anatase TiO2

TiO2-supported catalysts have been widely used for a range of both liquid-phase and gas-phase hydrogenation reactions. However, little is known about the effect of their different crystalline surfaces on their activity during the hydrodeoxygenation process. In this work, Au supported on anatase TiO2, mainly exposing 101 or 001 facets, was investigated for the hydrodeoxygenation (HDO) of guaiacol. At 300 °C, the strong interaction between the Au and TiO2-101 surface resulted in the facile reduction of the TiO2-101 surface with concomitant formation of oxygen vacancies, as shown by the H2-TPR and H2-TPD profiles. Meanwhile, the formation of Auδ−, as determined by CO-DRIFT spectra and in situ XPS, was found to promote the demethylation of guaiacol producing methane. However, this strong interaction was absent on the Au/TiO2-001 catalyst since TiO2-001 was relatively difficult to be reduced compared with TiO2-101. The Au on TiO2-001 just served as the active site for the dissociation of hydrogen without the formation of Auδ−. The hydrogen atoms spilled over to the surface of TiO2-001 to form a small amount of oxygen vacancies, which resulted in lower activity than that over Au/TiO2-101. The catalytic activity of the Au/TiO2 catalyst for hydrodeoxygenation will be controlled by tuning the crystal plane of the TiO2 support.