Delignified rice husk waste (25.66% (wt) cellulose) was converted to levulinic acid using three types of manganese catalysts, i.e., the Mn3O4/hierarchical ZSM-5 zeolite and Mn3O4 heterogenous catalysts, as well as Mn(II) ion homogeneous counterpart. The hierarchical ZSM-5 zeolite was prepared using the double template method and modified with Mn3O4 through wet-impregnation method. The structure and physicochemical properties of the catalyst materials were determined using several solid-state characterization techniques. The reaction was conducted in a 200 mL-three neck-round bottom flask at 100 °C and 130 °C for a certain reaction time in the presence of 10% (v/v) phosphoric acid and 2% (v/v) H2O2 aqueous solution, and the product was analyzed using HPLC. In general, 5-hydroxymethyl furfural (5-HMF) as the intermediate product was produced after 2 h and decreased after 4 h reaction time. To conclude, the Mn3O4/hierarchical ZSM-5 heterogenous catalyst gave the highest yield (wt %) of levulinic acid (39.75% and 27.60%, respectively) as the main product, after 8 h reaction time.

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Lignin isolated from wood waste biomass, contains 61.07 % of lignin, was converted to vanillin using ZSM-5 catalysts. Prior to use, wood waste biomass was delignified to enrich its lignin contents followed by added 10 % H2SO4 to isolate the lignin such as solid black material. Three types of ZSM-5 catalysts i.e. hierarchical ZSM-5, NiO/hierarchical ZSM-5 and CuO/hierarchical ZSM-5 zeolites were used as catalysts in this study. Hierarchical ZSM-5 zeolite was prepared through TPAOH template synthesis methods followed by PDDAM as secondary template. Silicate and aluminate source based on a natural source to form hierarchical ZSM-5 zeolite. Hierarchical ZSM-5 zeolite is modified with NiO and CuO by using impregnation method with Ni nitrate and Cu nitrate solution followed by calcination at 550 °C. The characterization of catalysts employed FTIR, XRD, andSEM-EDX. The reaction was carried out in 200 mL-batch reactor at 100 °C, 150 °C, 200 °C, 250 °C and 300 °C in the presence of ethanol and water (v/v) for 30 min. CuO/hierarchical ZSM-5 zeolite gave the highest % yield of vanillin as product (4.68 %) followed by NiO/hierarchical ZSM-5 zeolite (3.82 %) for the variation of temperature, compared to other ZSM-5 catalysts.

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