Synthesis of bio-based methylcyclopentadiene via direct hydrodeoxygenation of 3-methylcyclopent-2-enone derived from cellulose

The exploration of highly efficient processes to convert renewable biomass to fuels and value-added chemicals is stimulated by the energy and environment problems. Herein, we describe an innovative route for the production of methylcyclopentadiene (MCPD) with cellulose, involving the transformation of cellulose into 3-methylcyclopent-2-enone (MCP) and subsequent selective hydrodeoxygenation to MCPD over a zinc-molybdenum oxide catalyst. The excellent performance of the zinc-molybdenum oxide catalyst is attributed to the formation of ZnMoO3 species during the reduction of ZnMoO4. Experiments reveal that preferential interaction of ZnMoO3 sites with the C=O bond instead of C=C bond in vapor-phase hydrodeoxygenation of MCP leads to highly selective formations of MCPD (with a carbon yield of 70%).


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Supplementary Figure 14. TG profiles of the ZnO support which was reduced at 400°C for 2 h.

Calculation method for the oxygen vacancy concentrations of the catalysts:
On the one hand, the mass fraction of Mo

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Supplementary Figure  In the TG curve, the fresh 15wt.%MoO3/ZnO catalyst exhibits a slight weight loss at full temperature region (30−800°C), while the used 15wt.%MoO3/ZnO catalyst gives a significant weight loss at a high temperature region (380-500°C). The weight loss at low temperature may be attributed to the desorption of water and reactant (or by-products), while the weight loss at the high temperature region should be related to the oxidation of coke formed on the catalyst. At higher temperature (> 500°C), the increasing of total weight for used 15wt.%MoO3/ZnO can be attributed to the oxidation of reduced 15wt.%MoO3/ZnO.

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Supplementary Figure 18. Diagram of the continuous flow reactor used in MCP hydrodeoxygenation.
In each test, a certain amount of catalyst was put into the tubular reactor. To keep the catalyst located at the constant temperature area, both top and end of the reactor were filled with quartz sand and quartz wool. After the system pressure and temperature are stabilized, the liquid reactant was pumped into the system at a certain flow rate using a high-pressure liquid chromatography pump (HPLC), accompanied with the hydrogen. The hydrogen flow rate was controlled by a mass flow controller (MFC). After coming out from the reactor and being cooled down in a trap, the product was divided into two phases through a gas-liquid separator. The gas phase products were analyzed online though a gas chromatography (GC) after passing through the back pressure regulator. According to the concentration of feed (or specific compound) in the gas phase effluent products (measured with the on-line GC by external standard method), the gas flowrate of the effluent gas and reaction time, we can calculate the mole amount of feed (or specific compound) in gas phase products. The liquid product was taken out through the sampling valve, and then analyzed by another GC using 1,4-dioxane as the internal standard.
According to the analysis results, we can calculate the mole amount of feed (or specific compound) detected in the liquid phase products. Thus, the conversion and selectivity of the reactions were calculated based on the analysis of gas phase products and liquid phase products according the following equations: Conversion (%) = 100total mole amount of feed detected in gas phase and liquid phase products / mole amount of feed pumped into reactor × 100 Selectivity for a specific compound (%) = total mole amount of a specific compound detected in gas phase and liquid phase products / total mole amount of feed converted × 100 Based on our analysis, the carbon balances of this work are good. In most of cases, the sum of selectivity of identified products are higher than 80%.
In the reaction system, the packing volume of 2.5 g catalyst is 1.6 mL. The initial H2/MCP molar ratio used in MCP hydrodeoxygenation is 40. The reaction temperature (400 o C) is higher than the boiling point of MCP (157.5 o C). Therefore, when H2 flow rate is 90 mL min -1 , the flow rate of the MCP after being vaporized in tubular reactor is 2.25 (i. e., 90 / 40) mL min -1 . The residence time (t) of MCP on the catalyst is t = the packing volume of catalyst / the flow rate of MCP after being vaporized = 1.6 mL / 2.25 mL min -1 = 0.711 min = 42.67 s.