Conversion of biomass to chemicals over zirconium phosphate-based catalysts

1.IntroductionCatalysis is an important phenomenon in nature and is involvedin all areas of the chemical industry.Homogeneous andheterogeneous catalysis are key techniques in chemical production.The development of efficient,stable,and environmentallyfriendly catalytic methods is receiving much attentionbecause of the increasing global shortage of energy and seriousenvironmental damage.A number of efforts have been made inthe past for designing rationally catalysts to achieve desirablecatalytic activities,selectivities,and stabilities for specific reactions[1].The current energy crisis is affecting economies inevery region,particularly in fossil‐oil‐consuming countries,because of rapidly decreasing available stocks,therefore biomassconversion to fuels and chemicals using various approaches,including thermal,biological,and chemocatalyticprocesses,is attracting great attention worldwide[2].

Vicinal hydroxyl group-inspired selective oxidation of glycerol to glyceric acid on hydroxyapatite supported Pd catalyst

Selective oxidation of glycerol provides a feasible route towards the sustainable synthesis of high value-added chemicals.Herein,the hydroxyapatite(HAP)supported palladium(Pd)species were fabricated by impregnation and subsequent calcination.The as-obtained heterogeneous Pd catalyst afforded not only excellent selectivity to glyceric acid(GLA)up to 90%with 59%conversion of glycerol but also good recyclability by using molecular oxygen as an oxidant under mild conditions.The characterization of catalysts indicated that both the surface basicity and Pd sites on the catalyst played a crucial role in promoting glycerol oxidation.Notably,it demonstrated that the presence of the vicinal hydroxyl group of glycerol molecule can assist the oxidation reaction via forming a coordination between the vicinal hydroxyl group and Ca^(2+) sites on HAP-derived catalysts.In this catalytic process,the secondary hydroxyl of glycerol kept untouched and the primary hydroxyl of glycerol was converted into carboxyl group,while the Pd species acted as active centers for cooperatively promoting the subsequent oxidation to generate GLA.Additionally,this catalytic system can be extended widely for the oxidative conversion of other vicinal diols into the corresponding a-hydroxycarboxylic acids selectively.Isotope labeling experiment using H_(2)^(18)O confirmed that H_(2)O not only acted as solvent but also was involved in the catalytic cycles.On the basis of the results,a possible reaction mechanism has been proposed.The HAP-supported Pd catalytic system has been shown to serve as an effective approach for the upgrading of bio-derived vicinal diols to high value-added chemicals.

Energy status regulated umami compound metabolism in harvested shiitake mushrooms(Lentinus edodes)with spores triggered to release

The molecular mechanisms of energy status related to the umami taste of postharvest shiitake mushrooms during spore release remain poorly understood.In this study,the variations of energy status and umami taste of mushrooms were measured at 25℃.At 24 h storage,slight spore prints of mushrooms were first pictured,respiration peaked.Significant ATP decrease and ADP increase were also observed as the initiation of postharvest senescence(P<0.05).Meanwhile,the activities of phosphohexose isomerase,succinate dehydrogenase,glucose-6-phosphate dehydrogenase and cytochrome c oxidase and the contents of umami nucleotides and amino acids were maintained at higher levels in mushrooms with spore release.Notably,the equivalent umami concentration(EUC)was strongly correlated with energy levels(R=0.80).Fifteen related gene expression levels in the energy metabolism pathway were downregulated.LecpdP1 and LeAK were significantly expressed in the conversion of ATP into AMP and played key roles in connecting the energy state and umami level.These results provided valuable insights on the umami taste associated with energy metabolism mechanism during postharvest mushroom spore release.

Aluminum(Ⅲ) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide

Glycerol is a by-product of biodiesel production and is an important readily available platform chemical.Valorization of glycerol into value-added chemicals has gained immense attention.Herein,we carried out the conversion of glycerol to formic acid and glycolic acid using H2O2 as an oxidant and metal(Ⅲ)triflate-based catalytic systems.Aluminum(Ⅲ)triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid.A correlation between the catalytic activity of the metal cations and their hydrolysis constants(Kh)and water exchange rate constants was observed.At 70 ℃,a formic acid yield of up to 72% could be attained within 12 h.The catalyst could be recycled at least five times with a high conversion rate,and hence can also be used for the selective oxidation of other biomass platform molecules.Reaction kinetics and 1H NMR studies showed that the oxidation of glycerol(to formic acid)involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products.Both the [Al(OH)x]^n+ Lewis acid species and CF3SO3H Brosted acid,which were generated by the in-situ hydrolysis of Al(OTf)3,were responsible for glycerol conversion.The easy availability,high efficiency,and good recyclability of Al(OTf)3 render it suitable for the selective oxidation of glycerol to high value-added products.

Sexual spores in edible mushroom: bioactive components, discharge mechanisms and effects on fruiting bodies quality

Edible mushroom sexual spores have been gaining more interest due to their bioactive components and functions.Spore discharge(SD)is an important factor affecting the quality of edible mushrooms.In this review,the bioactive nutrients of sexual spores of edible mushrooms were summarized,the SD mechanism was described,and the relationship between postharvest SD and the quality of edible mushrooms was analyzed.Spores contain various bioactive nutrients that are benefi cial to the human body.Mature mushrooms can actively discharge spores in a process affected by light,relative humidity,and temperature.During storage,the physiological metabolism of spore-bearing gill tissue is vigorous,promoting the release of postharvest spores and changing the nutritional value of fruiting bodies.The flavor of the fruiting bodies also varied signifi cantly during SD.Edible mushroom sexual spores have the potential to become new raw materials for functional food and medical resources.Research on the effect of the mechanism of SD on the quality of edible mushrooms and the development of SD regulation technology may be a new trend in the quality control of edible mushrooms,which will promote the development of the edible mushroom industry.

Catalytic transfer hydrogenolysis of C–O bonds in lignin model compounds without arene hydrogenation

The shortage of resources and the destruction of the environment have caused serious resource and environmental problems shared by all countries around the world. As a ubiquitous renewable resource, biomass has great prospects for replacing fossil energy and attracted attention from the society. The use of catalytic approach to transform biomass into high-value chemicals is an effective way to use biomass efficiently. In this work, Nisupported catalysts has been developed for the selective cleavage of C–O bonds in lignin model compounds with 2-propanol as the hydrogen source solvent. Among these catalysts, it was indicated that zirconium phosphate(Zr P)-supported Ni catalysts were highly efficient and recyclable for alkyl-aryl ether(α-O-4 and β-O-4) cleavage in lignin model compounds. The further investigation demonstrated that the transfer hydrogenolysis of the C–O bond is highly selective, which afforded phenols and aromatics as dominant products without the products arising from hydrogenation of aromatic rings. Through a series of characterization of the catalyst, it was demonstrated that the medium strong acid sites of the Zr P support promoted the cleavage of alkyl-aryl ethers(α-O-4 and β-O-4),and Br?nsted acid sites favored for achieving high selectivity toward C–O bond cleavage. Additionally, Ni(0) sites on the Zr P catalysts were responsible for the catalytic transfer hydrogenolysis.

Cationic quaternary ammonium-stabilized Nb oxoclusters catalyze reductive amination of carbon dioxide with hydrosilane

The N-formylation of amines with CO_(2)and hydrosilanes is an emerging yet important reaction in fine chemical industry.Herein,we have reported a methyltrioctylammonium cation(TOMA)stabilized Nb oxocluster catalyst that can effectively realize two electron reduction of CO_(2)and form C-N bond simultaneously,leading to the corresponding formamides.The oxocluster catalyst exhibits excellent catalytic activity to transform secondary and primary amines into the corresponding formamides,with the conversion ranging from 81.5%to 99.2%under room temperature conditions.Furthermore,the Nb oxocluster catalyst shows the unique characteristics of ionic liquids,and it is highly robust and easy to be recycled for five times with negligible loss of catalytic activity.On the basis of the activity tests and structure characterization of Nb catalysts,it was found that TOMA cation played an important role in modulating the Nb oxocluster with high stability and uniform dispersion.The mechanism studies demonstrate that the formylation reaction proceeds through the formation of silyl formate intermediate rather than carbamate,and the Lewis base site of negative oxygen atoms from polyoxoniobate anions can exert a favorable impact on activation both CO_(2)and Si-H bond of PhSiH 3,allowing that N-formylation reaction proceed smoothly under very mild reaction conditions.

Effect of mushroom root fermentation broth on the umami taste and nutrients of Flammulina velutipes

As one of the most appealing edible mushrooms,the quality of Flammulina velutipes can be affected by the cultivation substrate,which has an impact on the mushroom umami taste and nutrients.In our study,the effect of mushroom root fermentation broth(MRFB)based substrate on umami taste and nutrients of F.velutipes were evaluated;four proportions of MRFB were conducted(CK 0%,E16.7%,E213.4%,E320.1%).Results indicated that MRFB was an effective nutrient supplement for mushroom cultivation substrate.E2 and E3 showed higher crude fiber,crude fat,and soluble protein.Compared to CK,the content of monosodium glutamate-like(MSG-like)amino acids,essential amino acids,total amino acids,and total 5′-nucleotides in E2 and E3 were higher.The equivalent umami concentration(EUC)values in E1,E2 and E3 were 1.70,2.43 and 1.56 times that of CK,respectively.Higher umami,saltness and sweetness taste values were found in E2.Thereby,it signified that better umami and richer nutrients were achieved by using substrate with proper volume of MRFB,especially,E2 with 13.4%of MRFB.Overall,better mushroom quality could be derived from the application of MRFB in cultivation.MRFB was a favorable nutrient supplement for F.velutipes cultivation substrate.