Direct conversion of furfural to levulinic acid/ester in dimethoxymethane: Understanding the mechanism for polymerization

Sun

et al. 2019

Energy Tech

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Distinct crystal phases of an oxide affect the configuration of surface atoms, which might further affect coordination with sulfate during sulfonation for the preparation of SO42−/MxOy type of acid catalyst. Herein, such an effect is investigated with zirconia of the tetragonal or monoclinic phase as the model catalysts. The results show that sulfonation inhibits the transformation of zirconia from the tetragonal phase to the monoclinic phase, whereas the varied phase of zirconia also affects the bonding patterns of sulfate species with zirconia in sulfonation. The sulfated zirconia of monoclinic phase contains more abundant acidic sites and more Brønsted acid sites than that of sulfated zirconia of tetragonal phase. Consequently, the sulfated zirconia of monoclinic phase is more active than the sulfated zirconia of tetragonal phase for the conversion of furfuryl alcohol in ethanol and conversion of fructose in dimethyl sulfoxide, achieving the yield of ethyl levulinate of 96.4% and a high yield of 5‐hydroxymethylfurfural. The sulfated zirconia is not stable in protic solvent due to the leaching of sulfur species and the change in configurations of the sulfate species and the zirconium species, but in the aprotic solvent, they show good stability and recyclability.

Section: Introductionmentioning

confidence: 99%

Sulfated Zirconia with Different Crystal Phases for the Production of Ethyl Levulinate and 5‐Hydroxymethylfurfural

Sun

et al. 2019

Energy Tech

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“…3(c). The characteristic peak at 3450 cm −1 was present in all samples, which was assigned to the hydroxyl group in the coordinated water or that in TiO 2 samples . Besides, the absorption peak at 1630 cm −1 related to OH bending vibration was also present in all catalysts .…”

Section: Resultsmentioning

confidence: 84%

“…The characteristic peak at 3450 cm −1 was present in all samples, which was assigned to the hydroxyl group in the coordinated water or that in TiO 2 samples. 36,37 Besides, the absorption peak at 1630 cm −1 related to OH bending vibration was also present in all catalysts. 38 Comparing TiO 2 and sulfated TiO 2 samples, the prominent difference was observed in the range from 1300 to 900 cm −1 , belonging to stretching vibration of S O and stretching of S O.…”

Section: Ftirmentioning

confidence: 81%

Sulfated TiO₂ nanosheets catalyzing conversion of biomass derivatives: influences of the sulfation on distribution of Brønsted and Lewis acidic sites

J of Chemical Tech & Biotech

Gao

et al. 2020

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BACKGROUND The synthesis of solid acid catalysts of recoverable and environmentally friendly nature has gained increasing attention in recent years. The distribution of Brønsted and Lewis acidic sites on the surface of sulfated metal oxides determines the catalytic performance, which is affected by many key factors, such as the concentration of sulfuric acid impregnated and the morphology of the metal oxides used. In this study, TiO2 nanosheets were successfully synthesized and used as carrier for the preparation of solid acid catalysts. RESULTS The concentration of sulfuric acid for the impregnation resulted in various distributions of Brønsted and Lewis acidic sites on the surface of sulfated TiO2. With a medium concentration of sulfuric acid (1 mol L−1) for the impregnation, the highest ratio of Brønsted to Lewis acidic sites can be achieved, and the catalyst showed superior catalytic activity for the conversion of furfuryl alcohol (FA) to ethyl levulinate (EL) in ethanol and the conversion of fructose to 5‐hydroxymethylfurfural (HMF) in dimethyl sulfoxide (DMSO). CONCLUSION The sulfation of TiO2 nanosheets induced the formation of both Brønsted and Lewis acidic sites. The Brønsted acidic sites were more effective for catalyzing the conversion of FA or fructose. The poor recyclability of the 1.0‐SO42−/TiO2 catalyst in the conversion of FA to EL in ethanol, a protic solvent, was due to the leaching of sulfur species. The deactivation of the catalyst in DMSO was due to coking, which could be resolved via calcination of the coke species in air. © 2019 Society of Chemical Industry

“…, when the loading of GO3 increase from 0.06% (entry 3) to 0.78% (entry 8), the proportion of intermediate products decreases significantly, and the peaks for 2‐(ethoxymethyl) furan (7.5 min) and 4,5‐diethoxypentan‐2‐one (12.1 min) almost disappear. In this case, the products present a black color, owing to the production of soluble polymer during the conversion process . In order to compare the catalyst activity, the commercial catalyst (D008) was employed, and the yield of EL catalyzed by D008 is from 62.9% to 74.2% with the acid amount from 0.06% to 0.78%.…”

Section: Resultsmentioning

confidence: 99%

“…In this case, the products present a black color, owing to the production of soluble polymer during the conversion process. 64 In order to compare the catalyst activity, the commercial catalyst (D008) was employed, and the yield of EL catalyzed by D008 is from 62.9% to 74.2% with the acid amount from 0.06% to 0.78%. The higher catalyst activity of D008 is benefited from the higher acidic group density (3.25 mmol g −1 ).…”

Section: Ea Analysismentioning

confidence: 99%

Design of graphene oxide by a one‐pot synthetic route for catalytic conversion of furfural alcohol to ethyl levulinate

J of Chemical Tech & Biotech

Jing

et al. 2019

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Background Graphene oxide (GO) has abundant oxygen‐containing functionalities such as hydroxyl groups and carboxyl groups with distinct acidities. This feature makes GO a potential solid acid catalyst for the acid‐catalyzed reactions such as the production of ethyl levulinate (EL), a platform chemical, from the acid‐treatment of furfuryl alcohol (FA). The structure and functionalities of GO are closely related to its catalytic performance, and thus it is necessary to establish the relationship between the chemical structure and the catalytic properties of GO. To achieve this aim, in this work, the GO catalysts were designed by a facile one‐pot synthetic route with no subsequent modification. By controlling the parameters of oxidation process in preparation, multiple functional groups were immobilized onto graphitic substrate, significantly impacting the catalytic activity of GO in the conversion of FA to EL in an ethanol (EtOH) medium. Results The results showed that, the oxidation process significantly influenced the distribution of oxygen‐containing functionalities on the surface of GO. The amount of the oxygen‐containing functionalities can be adjusted by the oxidation parameters such as oxidizing agent equivalent, reaction time and temperature, while the organosulfate can only be remained at a moderate oxidation temperature. The existence of the synergistic effect between the oxygen‐containing functionalities and the organosulfate functionalities promoted the catalytic activity of GO for the acid‐catalyzed conversion of FA to EL. Conclusions This work provides a new strategy of design and development of functional graphene‐based catalysts for the acid‐catalyzed reactions, and lays foundation of the practicability of GO in biomass conversion. © 2019 Society of Chemical Industry