Impact of Design on the Activity of ZrO2 Catalysts in Cellulose Hydrolysis-Dehydration to Glucose and 5-Hydroxymethylfurfural

The one-pot hydrolysis-dehydration of activated microcrystalline cellulose was studied in pure hydrothermal water at 453 K over ZrO2 catalysts produced by thermodegradation, microwave treatment, mechanical activation, and sol–gel methods and spent without any co-catalyst. ZrO2 prepared by microwave treatment was more active compared to ones derived by other methods. The catalyst calcination temperature also impacted reactivity. The cellulose conversion increased simultaneously with acidity and SBET, which in turn were set by the preparation method and calcination temperature. Phase composition did not affect the activity. Yields of glucose and 5-HMF reaching 18 and 15%, respectively, were over the most promising ZrO2 prepared by microwave treatment at 593 K. To our knowledge, this ZrO2 sample provided the highest activity in terms of TOF values (15.1 mmol g−1 h−1) compared to the pure ZrO2 systems reported elsewhere. High stability of ZrO2 derived by microwave irradiation was shown in five reaction runs.

Biomass-derived chemical substitutes for bisphenol A: recent advancements in catalytic synthesis

Bisphenol A is an oil-derived, large market volume chemical with a wide spectrum of applications in plastics, adhesives and thermal papers. However, bisphenol A is not considered safe due to its endocrine disrupting properties and reproductive toxicity. Several functional substitutes of bisphenol A have been proposed in the literature, produced from plant biomass. Unless otherwise specified, the present review covers the most significant contributions that appeared in the time span January 2015-August 2019, describing the sustainable catalytic synthesis of rigid diols from biomass derivatives. The focus is thereupon on heterogeneous catalysis, use of green solvents and mild conditions, cascade processes in one-pot, and continuous flow setups. More than 500 up-to-date references describe the various substitutes proposed and the catalytic methods for their manufacture, broken down according to the main biomass types from which they originate.

Towards Sustainable Production of Formic Acid

Formic acid is a widely used commodity chemical. It can be used as a safe, easily handled, and transported source of hydrogen or carbon monoxide for different reactions, including those producing fuels. The review includes historical aspects of formic acid production. It briefly analyzes production based on traditional sources, such as carbon monoxide, methanol, and methane. However, the main emphasis is on the sustainable production of formic acid from biomass and biomass-derived products through hydrolysis and oxidation processes. New strategies of low-temperature synthesis from biomass may lead to the utilization of formic acid for the production of fuel additives, such as methanol; upgraded bio-oil; γ-valerolactone and its derivatives; and synthesis gas used for the Fischer-Tropsch synthesis of hydrocarbons. Some technological aspects are also considered.

Cellulose Biorefinery Based on a Combined Catalytic and Biotechnological Approach for Production of 5-HMF and Ethanol

In this study, a combination of catalytic and biotechnological processes was proposed for the first time for application in a cellulose biorefinery for the production of 5-hydroxymethylfurfural (5-HMF) and bioethanol. Hydrolytic dehydration of the mechanically activated microcrystalline cellulose over a carbon-based mesoporous Sibunt-4 catalyst resulted in moderate yields of glucose and 5-HMF (21.1-25.1 and 6.6-9.4 %). 5-HMF was extracted from the resulting mixture with isobutanol and subjected to ethanol fermentation. A number of yeast strains were isolated that also revealed high thermotolerance (up to 50 °C) and resistance to inhibitors found in the hydrolysates. The strains Kluyveromyces marxianus C1 and Ogataea polymorpha CBS4732 were capable of producing ethanol from processed catalytic hydrolysates of cellulose at 42 °C, with yields of 72.0±5.7 and 75.2±4.3 % from the maximum theoretical yield of ethanol, respectively.