Hydrodeoxygenation of palm oil to green diesel products on mixed-phase nickel phosphides

Engineering Lewis-Acid Defects on ZnO Quantum Dots by Trace Transition-Metal Single Atoms for High Glycerol-to-Glycerol Carbonate Conversion

Efficient conversion of biomass wastes into valuable chemicals has been regarded as a sustainable approach for green and circular economy. Herein, a highly efficient catalytic conversion of glycerol (Gly) into glycerol carbonate (GlyC) by carbonylation with the commercially available urea is presented using low-cost transition metal single atoms supported on zinc oxide quantum dots (M1-ZnO QDs) as a catalyst without using any solvent. A facile one-step wet chemical synthesis allows various types of metal single atoms to simultaneously dope and introduce Lewis-acid defects in the ZnO QD structure. It is found that doping with a trace amount of isolated metal atoms greatly boosts the catalytic activity with Gly conversion of 90.7%, GlyC selectivity of 100.0%, and GlyC yield of 90.6%. Congruential results from both Density Functional Theory (DFT) and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) studies reveal that the superior catalytic performance can be attributed to the enriched Lewis acid sites that endow optimal adsorption, formation of the intermediate for coupling between urea and Gly, and desorption of GlyC. Moreover, the tiny size of ZnO QDs efficiently promotes the accessibility of these active sites to the reactants.

Direct Production of Sustainable Aviation Fuel by Deoxygenation and Isomerization of Triglycerides Over Bifunctional Ir-ReOx/SAPO-11 Catalyst

Catalytic thermochemical conversion offers a sustainable method to upgrade oil-based feedstocks into highly valuable biofuel, aligning with the modern biorefinery concept. Herein, a series of IrRe/SAPO-11 catalysts with different Ir to Re molar ratios compared to reference Ir/SAPO-11 and Re/SAPO-11 catalysts was prepared using a wetness impregnation method. These catalysts were used for the direct production of sustainable aviation fuels (SAFs) via efficient hydrodeoxygenation and hydroisomerization of triglycerides. The catalyst screening confirmed that the optimum IrRe/SAPO-11 catalyst, with an equivalent Ir to Re molar ratio, exhibited the highest hydrodeoxygenation activity under milder operation conditions than the conditions used in previous studies. Increasing the reaction temperature up to 330 °C enhanced the formation of iso-alkanes in the liquid product, achieving a freezing point of -31.4 °C without additional cold flow improvers. Furthermore, a long-term stability experiment demonstrated that the developed Ir-Re system exhibited exceptional performance over 150 h. This excellent catalytic activity and stability of the bifunctional IrRe/SAPO-11 catalyst was owing to its suitable interface between metallic and oxide sites, mixed mesoporous structures, reduced catalyst size, and increased Lewis acid ratio, as confirmed by our comprehensive characterizations.

Selective Deoxygenation of Waste Cooking Oil to Diesel-Like Hydrocarbons Using Supported and Unsupported NiMoS2 Catalysts

This work aimed to study the deoxygenation of two different waste cooking oils (WCOs; palm oil and soybean oil) using alumina (γ-Al2O3)-supported and unsupported NiMoS2 catalysts prepared by the hydrothermal method. The variables evaluated in this study were the reactant concentration, reaction time, and nickel (Ni)/[Ni + molybdenum (Mo)] atomic ratio (0.2 and 0.3) affecting the yield and selectivity of alkane products. The supported NiMo sulfide (NiMoS2)/γ-Al2O3 catalyst prepared by impregnation had the drawback of a lack of layers and stacks, so combining the γ-Al2O3 with unsupported NiMoS2 catalysts using a hydrothermal method was evaluated. The main products obtained from the deoxygenation of the two WCOs were normal (n-)alkane compounds (C15, C16, C17, and C18). The catalyst efficiency was ranked as 0.2-NiMoS2/γ-Al2O3 ≈ 0.2-NiMoS2 > 0.3-NiMoS2/γ-Al2O3 ≈ 0.3-NiMoS2. The catalyst that gave the high n-C15-C18 yield was 0.2-NiMoS2/γ-Al2O3 under a reaction condition of 300 °C, 40 bar initial H2 pressure, and oil concentration of 5 wt %. For the hydrodeoxygenation (HDO) of waste palm oil, the n-C14-C18 yield was 56.4% (C14, C15, C16, C17, and C18 at 1.3, 6.7, 14.5, 11.8, and 22.1%, respectively), while that for the waste soybean oil was 58% (C14, C15, C16, C17, and C18 at 1.1, 3.8, 6.7, 17.2, and 29.2%, respectively). The n-C18/n-C17 and n-C16/n-C15 ratios were both greater than 1 for both types of WCO, revealing that the deoxygenation mainly proceeded via HDO rather than decarbonylation and decarboxylation. The 5-10% lower n-C14-C18 yield from the waste oil compared with the fresh oil was acceptable, implying the effective oil treatment and some impurity removal.

Atomic Cu-N-P-C Active Complex with Integrated Oxidation and Chlorination for Improved Ethylene Oxychlorination

Fine constructing the chemical environment of the central metal is vital in developing efficient single-atom catalysts (SACs). Herein, the atomically dispersed Cu on the N-doped carbon is modulated by introducing CuP moiety to CuNC SAC. Through fine-tuning with another heteroatom P, the Cu SAC shows the superior performance of ethylene oxychlorination. The Cu site activity of Cu-NPC is four times higher than the P-free Cu-NC catalyst and 25 times higher than the Ce-promoted CuCl₂ /Al₂ O₃ catalyst in the long-term test (>200 h). The selectivity of ethylene dichloride can be splendidly kept at ≈99%. Combined experimental and simulation studies provide a theoretical framework for the coordination of Cu, N, and P in the complex active center and its role in effectively catalyzing ethylene oxychlorination. It integrates the oxidation and chlorination reactions with superior catalytic performance and unrivaled ability of corrosive-HCl resistance. The concept of fine constructing with another heteroatom is anticipated to provide with inspiration for rational catalyst design and expand the applications of carbon-based SACs in heterogeneous catalysis.

Hydrocracking of crude palm oil to a biofuel using zirconium nitride and zirconium phosphide-modified bentonite

In this study, bentonite modified by zirconium nitride (ZrN) and zirconium phosphide (ZrP) catalysts was studied in the hydrocracking of crude palm oil to biofuels. The study demonstrated that bentonite was propitiously modified by ZrN and ZrP, as assessed by XRD, FTIR spectroscopy, and SEM-EDX analysis. The acidity of the bentonite catalyst was remarkably enhanced by ZrN and ZrP, and it showed an increased intensity in the Lewis acid and Brønsted acid sites, as presented by pyridine FTIR. In the hydrocracking application, the highest conversion was achieved by bentonite-ZrN at 8 mEq g⁻¹ catalyst loading of 87.93%, whereas bentonite-ZrP at 10 mEq g⁻¹ showed 86.04% conversion, which suggested that there was a strong positive correlation between the catalyst acidity and the conversion under a particular condition. The biofuel distribution fraction showed that both the catalysts produced a high bio-kerosene fraction, followed by bio-gasoline and oil fuel fractions. The reusability study revealed that both the catalysts had sufficient conversion stability of CPO through the hydrocracking reaction up to four consecutive runs with a low decrease in the catalyst activity. Overall, bentonite-ZrN dominantly favored the hydrocracking of CPO than bentonite-ZrP.

In this study, bentonite modified by zirconium nitride (ZrN) and zirconium phosphide (ZrP) catalysts was studied in the hydrocracking of crude palm oil to biofuels.

Theoretical Investigation of the Deactivation of Ni Supported Catalysts for the Catalytic Deoxygenation of Palm Oil for Green Diesel Production

For the first time, a fully comprehensive heterogeneous computational fluid dynamic (CFD) model has been developed to predict the selective catalytic deoxygenation of palm oil to produce green diesel over an Ni/ZrO2 catalyst. The modelling results were compared to experimental data, and a very good validation was obtained. It was found that for the Ni/ZrO2 catalyst, the paraffin conversion increased with temperature, reaching a maximum value (>95%) at 300 °C. However, temperatures greater than 300 °C resulted in a loss of conversion due to the fact of catalyst deactivation. In addition, at longer times, the model predicted that the catalyst activity would decline faster at temperatures higher than 250 °C. The CFD model was able to predict this deactivation by relating the catalytic activity with the reaction temperature.