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Synthetic fragrance has dominated the perfumery industry in recent decades due to the ability to produce perfumery ingredients on a large scale at a low cost. Extensive research in the field of synthetic perfumery chemical involved the utilization of catalysts to improve the productivity. This review will discuss recent advances of heterogeneous catalysts for the synthesis of perfumery chemicals as fragrance ingredients. Transition from homogeneous to heterogeneous catalysts will be included in order to provide insight into the benefits of heterogeneous catalysts to overcome the limitation of homogeneous reaction. Isomerization, acetalization and hydrogenation were identified as three main reactions for the synthesis of perfumery chemicals based on the number of reported work since 2000. This review will focus on α‐pinene and α‐pinene oxide as the main molecular substrates, however, different molecules, for example, linalool, citronellal and cinnamaldehyde will also be included. The synthesis, modification and possible mechanisms for the reactions involving zeolite, aluminosilicate, metal oxides, metal organic framework, monometallic and bimetallic nanoparticles as heterogeneous catalysts will be discussed. Discussion on isomerization and acetalization reactions will focus on the acidity and the porosity of the catalysts as the two main factors that determine the conversion and selectivity. For perfumery chemicals produced via hydrogenation reaction, the role of monometallic and bimetallic nanoparticles catalysts will be discussed in the chemoselective reduction of cinnamaldehyde and citronellal. [ABSTRACT FROM AUTHOR]

Background: Over the last few years, valorization of lignocellulosic biomass has been expanded beyond the production of second-generation biofuels to the synthesis of numerous platform chemicals to be used instead of their fossil-based counterparts. One such well-researched example is 5-hydroxymethylfurfural (HMF), which is preferably produced by the dehydration of fructose. Fructose is obtained by the isomerization of glucose, which in turn is derived by the hydrolysis of cellulose. However, to avoid harsh reaction conditions with high environmental impact, an isomerization step towards fructose is necessary, as fructose can be directly dehydrated to HMF under mild conditions. This work presents an optimized process to produce fructose from beechwood biomass hydrolysate and subsequently convert it to HMF by employing homogeneous catalysis. Results: The optimal saccharification conditions were identified at 10% wt. solids loading and 15 mg enzyme/gsolids, as determined from preliminary trials on pure cellulose (Avicel® PH-101). Furthermore, since high rate glucose isomerization to fructose requires the addition of sodium tetraborate, the optimum borate to glucose molar ratio was determined to 0.28 and was used in all experiments. Among 20 beechwood solid pulps obtained from different organosolv pretreatment conditions tested, the highest fructose production was obtained with acetone (160 °C, 120 min), reaching 56.8 g/100 g pretreated biomass. A scale-up hydrolysis in high solids (25% wt.) was then conducted. The hydrolysate was subjected to isomerization eventually leading to a high-fructose solution (104.5 g/L). Dehydration of fructose to HMF was tested with 5 different catalysts (HCl, H3PO4, formic acid, maleic acid and H-mordenite). Formic acid was found to be the best one displaying 79.9% sugars conversion with an HMF yield and selectivity of 44.6% and 55.8%, respectively. Conclusions: Overall, this work shows the feasibility of coupling bio- and chemo-catalytic processes to produce HMF from lignocellulose in an environmentally friendly manner. Further work for the deployment of biocatalysts for the oxidation of HMF to its derivatives could pave the way for the emergence of an integrated process to effectively produce biobased monomers from lignocellulose. [ABSTRACT FROM AUTHOR]

A strategy has been developed for the synthesis of ferrierite (FER) zeolites possessing strong acid sites (SAS) with different strength by using silica sol modified by different amounts of hydrochloric acid (HCl) as silicon source. The effect of HCl-modified silica sol on FER zeolite was investigated by XRD, ICP-AES, SEM, N2 adsorption–desorption, NH3-TPD and Py-IR. Moreover, some typical samples were evaluated in the reaction of 1-butene skeletal isomerization and the coke properties of the deactivated samples were analyzed by TG-MS and Raman spectroscopy. The results revealed that FER zeolite possessing weak SAS has excellent catalytic performance in the reaction of skeletal isomerization of 1-butene. Whereas FER zeolite with moderate SAS exhibits poor stability. By contrast, FER zeolite exhibiting SAS with high strength is easy to promote oligomerization-cracking reaction and reduce isobutene selectivity. Conversely, these findings also confirmed the effectiveness of the strategy for controlling the strength of SAS of FER zeolite. [ABSTRACT FROM AUTHOR]

Fructose is not only an important food and beverage ingredient, but also a renewable resource for production of bio-chemicals. In this paper, a series of N doped mesoporous carbon materials (MCNs) were prepared and evaluated as heterogeneous catalysts for catalytic isomerization of glucose to fructose. The MCNs were prepared through carbonization of p-phenylenediamine disulfate and the effects of desulfonation with NaOH and hydrogenation treatments were examined. It is found that the molar ratio of H2SO4/pPDA crucially affects the porous structure and the nitrogen content. Desulfonation with NaOH treatment could largely eliminate the sulfonic groups on the carbon edges and thus enhance the basicity of the MCN materials, whereas hydrogenation reduction could modify the N atom species and reinforce the strength of the basic sites, as a result enhancing the catalytic activities in glucose isomerization to fructose. Among all of the prepared MCN samples, MCN-2-DH showed an excellent activity in aqueous solution, which afforded a fructose yield of 31.6% with 84.6% selectivity. [ABSTRACT FROM AUTHOR]

The catalytic conversion of cellulosic biomass to downstream products provides a viable solution to alleviate the energy crisis and global warming. This article provides a relatively comprehensive review of the dehydration of glucose (the monomer of cellulose) and fructose considering various catalyst and solvent systems. Biphasic solvents and heterogeneous systems are recommended from the point of view of industrial applications. A two‐step catalytic conversion of glucose via fructose has been envisaged: first, isomerization of glucose to fructose, which has been extensively discussed in this review, and then transformation of fructose to downstream products. Two‐step tandem catalytic reactions from glucose to downstream products (i.e., one‐pot synthesis via fructose) are also attractive for industrial applications and should be given more attention. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Extra-large pore germanosilicate zeolite with UTL structure was tested in the n-decane hydroisomerization/hydrocracking reaction. The product selectivity demonstrated UTL to be the most open zeolite material ever characterized with the decane test. Al- and B-containing samples were synthesized with high degree of crystallinity. The incorporation of part of the heteroelements was confirmed with Al and B NMR spectroscopy. The catalytic activity and the structural stability of these samples was significantly lower compared to germanosilicate UTL and followed the sequence: UTL > Al-UTL > B-UTL. [ABSTRACT FROM AUTHOR]

The skeletal isomerization of n-butenes to isobutene has been carried out over ferrierite catalysts (Si/Al ~ 15) containing different acid sites distribution and different amount of defects. The zeolite crystals were synthesized under hydrothermal conditions in fluoride medium in the absence of alkaline cations by using suitable combinations of structure directing agents. Template-driven low density of acid sites in 10-membered-ring channels enhances the isobutene selectivity and decreases catalyst deactivation. The presence of high amount of silanol groups and Lewis acid sites increases the yields of by-products and catalysts decay. [ABSTRACT FROM AUTHOR]