Selective transfer hydrogenation of biomass derived furanic molecules using cyclohexanol as a hydrogen donor over nanostructured Cu/MgO catalyst

CO2-Assisted Controllable Synthesis of PdNi Nanoalloys for Highly Selective Hydrogenation of Biomass-Derived 5-Hydroxymethylfurfural

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-bishydroxymethyltetrahydrofuran (BHMTHF), a vital fuel precursor and solvent, is crucial for biomass refining. Herein, we report highly selective and stable PdNi nanoalloy catalysts for this deep hydrogenation process. A CO2-assisted green method was developed for the controllable synthesis of various bimetallic and monometallic catalysts. The PdNi/SBA-15 catalysts with various Pd/Ni ratios exhibited a volcano-like trend between BHMTHF yield and Pd/Ni ratio. Among all catalysts tested, Pd2Ni1/SBA-15 achieved the best performance, converting 99.0 % of HMF to BHMTHF with 96.0 % selectivity, surpassing previously reported catalysts. Additionally, the Pd2Ni1/SBA-15 catalyst maintained excellent stability even after five recycling runs. Catalyst characterizations (e. g., HAADF-STEM) and density functional theory (DFT) calculations confirmed the successful formation of the alloy structure with electron transfer between Ni and Pd, which accounts for the remarkable performance and stability of the catalyst. This work paves the way for developing highly selective and stable alloy catalysts for biomass valorization.

Comparative study on the reaction mechanism of 5-hydroxymethyl furfural on Pd(111) and Cu(111)

CONTEXT

In this work, a comparative study on the catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) on precious Pd(111) and nonprecious Cu(111) was systematically performed. On the basis of the calculated activation energy (Ea) and reaction energy (Er), the optimal energy path for the hydrogenation of HMF (F-CHO) into BHMF (F-CH2OH) on Pd(111) is as follows: F-CHO + 2H → F-CHOH + H → F-CH2OH; the minimum reaction path on Cu(111) is F-CHO + 2H → F-CH2O + H → F-CH2OH. On Cu(111), the formation of F-CH2OH from F-CH2O hydrogenation is the rate-determining step because it has the highest reaction energy barrier and the smallest rate constant. The comparison of HMF hydrogenation on Pd(111) and Cu(111) reveals their inherent differences in selectivity, mainly due to the different adsorption configurations of HMF and BHMF, and it was concluded that the nonprecious Cu(111) is a promising hydrogenation catalyst for the production of BHMF from the hydrogenation of HMF.

METHODS

All plane-wave DFT calculations were performed via the Vienna ab initio simulation package (VASP). The exchange and correlation energies were computed via the generalized gradient approximation (GGA) of the Perdew, Burke, and Ernzerhof (PBE) functional with the projector augmented wave (PAW) method.

A Review on the Critical Role of H2 Donor in the Selective Hydrogenation of 5-Hydroxymethylfurfural

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) has been of great interest to many scientists and researchers. However, conventional hydrogenation inevitably requires the use of gaseous hydrogen as a reducing agent, which is detrimental to its storage and transport. In this regard, other economical and environmentally friendly strategies, such as catalytic transfer hydrogenation/hydrogenolysis without external molecular H₂ , become more and more attractive. This Review provides the status and insight into the current research of hydrogenating HMF to high-value chemicals, using formic acid, alcohols, polymethylhydrosiloxane, water, and sodium borohydride as hydrogen donors and explains the hydrogenation mechanisms and the related hydrogenation characteristics of different hydrogen donors in the catalytic systems.

Continuous conversion of furfural to furfuryl alcohol by transfer hydrogenation catalyzed by copper deposited in a monolith reactor

A polymer monolith catalytic reactor, which is fabricated by anchoring –SO3H groups on the surface of the fibers and by depositing Cu species, exhibits outstanding performance and high stability in continuous transfer hydrogenation of furfural.