Hydrogenative Transformation Of Biobased Platform Compounds To Valued Added Chemicals For Environmental Resource Utilization

With the acceleration of the industrialization process,the consumption of fossil energy and the exposure of a series of environmental pollution problems,it has become a global consensus to turn to a low-carbon circular economy and implement a“carbon neutral”strategy.Recently,the upgradable conversion of renewable biomass platform compounds into high value-added chemicals through hydrogenation reactions has attracted extensive attention.In this paper,the synthesis methods of fine chemicals 2,5-dimethylfuran,cyclopentanone/alcohol,pyrrole and cyclopentenone were established.The mechanism of efficient hydrogenation and acid synergistic catalysis was systematically evaluated,the relationship between reaction performance and the composition of the catalyst,hydrogen activations as well as acids were deeply investigated.The main research subjects and conclusions as follow:（1）Herein,a class of Ni Co₂O₄ supported palladium with considerable oxygen defects was synthesized by hydrogen plasma etching and phosphating methods.The oxygen defects not only promote the hydrogenation of C=O group,but also enhances accessibility of coordinatively unsaturated metal cations with Lewis acidity for the hydrogenolysis of C-OH group.Meanwhile,the additional Br?nsted acidity in Pd/Ni Co₂O_4-x obtained by the phosphating can further strengthen the hydrogenolysis ability by etherification route of C-OH.Finally,Pd/Ni Co₂O_4-x exhibited the most effective performance with 2,5-dimethylfuran yield of 92.9%and 90.5%from 5-methylfurfural and 5-hydroxymethylfurfural,respectively.These catalytic mechanisms were confirmed by in situ infrared spectroscopy and control experiments.Furthermore,the catalyst showed outstanding recycling stability.This work shows a forceful synergistic catalysis in the hydrogenolysis reaction by multifunctional active sites.（2）Upgrading bioderived furfurals（furfural,5-hydroxymethylfurfural）to cyclopentanones（cyclopentanone,3-hydroxymethylcyclopentanone）and cyclopentanols（cyclopentanol,3-hydroxymethylcyclopentanol）is a representative bifunctional catalytic process in biomass conversion.Here,a class of Pd/Ni Mo O₄catalysts（Pd/Ni Mo O₄-Cl,Pd/Ni Mo O₄-AC）with low Pd loading（1.0 wt%）and different Pd dispersion are synthesized.The hydrogenation active sites and acidic sites of catalysts were adjusted by a water-mediated hydrogen spillover process.56.3-85.3%yields of cyclopentanones and 65.4-85.2%yields of cyclopentanols were obtained by hydrogenative ring-rearrangement route of furfurals over Pd/Ni Mo O₄-Cl and Pd/Ni Mo O₄-AC,respectively.This work presents an effective strategy for governing reaction routes and enhancing bifunctional catalysis with a hydrogen spillover mechanism.（3）Herein,Co-embedded N-doped carbon（Co@Co-NC）is used for the bifunctional catalytic conversion of furfurals to cyclopentanols.In addition to being a reductant for the hydrogenation step over Co nanoparticle core,H₂ can act as a catalyst to induce the acid-base transformation of Co-NC shell from Lewis acid-base pairs to Br?nsted acid-base pairs via heterolysis and a subsequent water-mediated mechanism,which largely promotes the acid-catalyzed step.Compared with Co/C,Co@Co-NC show a better bifunctional catalytic performance with cyclopentanol yields above 90%.This study redefines the role of H₂,which has important implications for many reduction reactions with water as a solvent.（4）Hence,an efficient one-pot synthesis for the conversion of biomass-derived furan alcohols（5-methylfurfuryl alcohol and 2,5-bis（hydroxymethyl）furan）and nitrobenzene derivatives to a variety of pyrroles and tetrahydropyrroles under mild reaction conditions for the first time was reported.Over-hydrogenated byproducts with a yield above 50%were generated over traditionally metal/acid support Pd/HZSM-5,due to competitive adsorption between intermediates of reaction substrates on hydrogen and acid sites.Whereas,the two trade-offs were perfectly avoided on metal phosphides.Ni Co P shows a considerable activity for the pyrroles with 90.4%yield,and Ni₂P exhibits a 60.3%yield of tetrahydropyrroles.Furthermore,after loading on the insert support,the catalyst displays outstanding stability and recycling performance after 4 runs.This work performs an effective strategy for governing reaction routes and shows the powerful synergistic effect of hydrogenation and acid catalysis.（5）For the synthesis of HCP,in comparison to conventional solid acids（i.e.,amberlyst-15）,MOFs with coordinatively unsaturated metal ions as pure Lewis acid sites exhibit advantageous catalytic selectivity in the reaction under an N₂ atmosphere in a bi-phasic water/n-hexane solvent system.Fe Zn and Fe Zn-P result in an HCP yield of 77.4%and 88.2%,respectively.For the CPE synthesis,the reaction conditions are the same as those for HCP,except a mono-phasic water solvent system and H₂atmosphere were employed.In addition to the acid-catalyzed rearrangement reaction,Fe Zn-PBA exhibits catalytic hydrogenation capability via heterolytic cleavage of the H-H bond over Zn-N frustrated Lewis pairs,and a CPE yield of 61.5%is obtained.The DFT simulation indicates that the acid sites and catalytic acid sites are ascribed to the tri-coordinatively unsaturated Zn²⁺site（Zn（N）₃）on the catalyst surface.Moreover,the PBA catalyst shows excellent stability and recycling performance.This work not only provides an efficient and green catalytic system for CPE and HCP preparation but also demonstrates the interesting bifunctional catalysis of both acid and hydrogenation catalysis over PBA.