Yetao Jiang

In Situ Generated Catalyst System to Convert Biomass‐Derived Levulinic Acid to γ‐Valerolactone

This is the first report of HCl/ZrO(OH)2 catalysts prepared in situ by the autonomous decomposition of ZrOCl2⋅8 H2O in levulinic acid (LA)/2‐butanol solution, which catalyzed the esterification of LA in tandem with hydrocyclization to γ‐valerolactone (GVL) by Meerwein–Ponndorf–Verley (MPV) reduction without the use of external H2. A maximum GVL yield of 92.4 % from neat LA and a GVL formation rate of 1092.2 μmol g−1 min−1 were achieved in 2‐butanol at 240 °C in 2 h. The in situ generated ZrO(OH)2 was characterized comprehensively and its unexpected catalytic efficiency was attributed mainly to its extremely high surface area. A crude LA stream from the acid hydrolysis of cellulose was extracted into 2‐butanol and subjected to this catalyst system to give a GVL yield of 82.0 % even in the presence of humins.

In Situ Catalytic Hydrogenation of Biomass‐Derived Methyl Levulinate to γ‐Valerolactone in Methanol

In this work, the hydrocyclization of methyl levulinate (ML) to γ-valerolactone (GVL) was performed in MeOH over an in situ prepared nanocopper catalyst without external H2 . This nanocopper catalyst served as a dual-functional catalyst for both hydrogen production by MeOH reforming and hydrogenation of ML. Nearly quantitative ML conversion with a GVL selectivity of 87.6 % was achieved at 240 °C in 1 h in MeOH under a nitrogen atmosphere. ML in the methanolysis products of cellulose also could be hydrogenated effectively to GVL over this nanocopper catalyst even in the presence of humins to give an ML conversion of 94.1 % and a GVL selectivity of 73.2 % at 240 °C in 4 h. The absorption behavior of humins on the surface of the nanocopper catalyst was observed, which resulted in a pronounced increase in the acidic sites of the nanocopper catalyst that facilitate ring-opening and the hydrocarboxylation/alkoxycarbonylation of GVL to byproducts.

Green catalytic conversion of bio-based sugars to 5-chloromethyl furfural in deep eutectic solvent, catalyzed by metal chlorides

Correction for ‘Green catalytic conversion of bio-based sugars to 5-chloromethyl furfural in deep eutectic solvent, catalyzed by metal chlorides’ by Miao Zuo et al., RSC Adv., 2016, 6, 27004–27007.

Methyl 4-methoxypentanoate: a novel and potential downstream chemical of biomass derived gamma-valerolactone

Lignocellulosic derived gamma-valerolactone was effectively converted into methyl 4-methoxypentanoate, a potential liquid biofuel, solvent and fragrance, by the catalysis of a hydrogen exchanged ultra-stable Y zeolite (HUSY) and insoluble carbonates such as CaCO3. The catalytic competing generation process between methyl 4-methoxypentanoate and pentenoate esters was also analysed.

Tandem thionation of biomass derived levulinic acid with Lawesson's reagent

Herein we report a tandem thionation of biomass derived levulinic acid (LA) to generate thiophenic compounds. LA is initially converted to several thiophenones and then an aromatic di-thionated product, 5-methylthiophene-2-thiol, is obtained with the highest yield of 78%. An overall synthesis of thiophenic products from cellulose is also developed.

Cooking with Active Oxygen and Solid Alkali: A Promising Alternative Approach for Lignocellulosic Biorefineries

Lignocellulosic biomass, a matrix of biopolymers including cellulose, hemicellulose, and lignin, has gathered increasing attention in recent years for the production of chemicals, fuels, and materials through biorefinery processes owing to its renewability and availability. The fractionation of lignocellulose is considered to be the fundamental step to establish an economical and sustainable lignocellulosic biorefinery. In this Minireview, we summarize a newly developed oxygen delignification for lignocellulose fractionation called cooking with active oxygen and solid alkali (CAOSA), which can fractionate lignocellulose into its constituents and maintain its processable form. In the CAOSA approach, environmentally friendly chemicals are applied instead of undesirable chemicals such as strong alkalis and sulfides. Notably, the alkali recovery for this process promises to be relatively simple and does not require causticizing or sintering. These features make the CAOSA process an alternative for both lignocellulose fractionation and biomass pretreatment. The advantages and challenges of CAOSA are also discussed to provide a comprehensive perspective with respect to existing strategies.

Chemical Structure Change of Magnesium Oxide in the Wet Oxidation Delignification Process of Biomass with Solid Alkali

We have developed a facile MgO‐based wet oxidation process for biomass pretreatment. Herein, we performed kilo‐scale experiments to elucidate the transformations of Mg in the process as well as the recycling of the MgO‐based solid alkali. A new intermediate, magnesium oxide carbonate [Mg3O(CO3)2] generated in situ during the process was shown for the first time, which could provide an indispensably weak but adequate alkaline environment to support the oxygen delignification reaction. However, once the solid alkali was transformed into hydromagnesite [Mg5(CO3)4(OH)2] with sufficient CO2, the hydromagnesite form would prevent the solid alkali from developing resistance to the acidic gaseous CO2. Ultimately, if we take the features of the solid alkali into consideration, alkali recovery for this process was fulfilled easily without concentration or causticization, which are of high cost but unavoidable in the traditional recycling of sodium alkali.

Cooking with active oxygen and solid alkali facilitates lignin degradation in bamboo pretreatment

Cooking with active oxygen and solid alkali (CAOSA), developed by our group, is a promising alternative to both clean pulping and biomass pretreatment since it is a facile technique with advantages of environmental benignity and easy alkali recovery. Through comparative analysis using 2D-HSQC NMR, the superior delignification efficiency of the CAOSA process could be attributed to the more efficient cleavage of the benzene ring in lignin, which is in sharp contrast to the conventional pulping route. Abundant organic acids were detected in the product solution, which is also known as yellow liquor (YL). In addition, acid insoluble degradation products (AIDPs) containing aromatic compounds were present in the YL, which were separated and collected. The low AIDP content in the YL suggested the highly efficient decomposition of the aromatic rings. This delignification study not only presents a deeper investigation of the CAOSA process itself but also provides guidance for further research on biomass-lignin degradation.