Catalytic dehydration of sorbitol and fructose by acid-modified zirconium phosphate

Enhanced Isopropyl Alcohol Conversion over Acidic Nickel Phosphate-Supported Zeolite Catalysts

In this preliminary research, the catalytic activity of isopropyl alcohol conversion to diisopropyl ether through dehydration reaction catalyzed by zeolite-Ni and zeolite-Ni(H₂PO₄)₂ was comparatively described. The natural zeolite was treated with 1% HF and 6 N HCl prior to modifications using the impregnation method. Isopropyl alcohol conversion was examined at a mild temperature of 150 °C for 3.5 h on the reflux system with various catalyst loadings. X-ray diffraction and Fourier transform infrared analysis confirmed the successful impregnation of nickel and nickel phosphate into the zeolite. Scanning electron microscopy analysis revealed a cubic-like structure on zeolite-Ni(H₂PO₄)₂, whereas homogenously distributed nickel species were observed on the zeolite-Ni catalyst. Energy-dispersive X-ray spectroscopy analysis reinforced the accomplishment of zeolite modifications. The N₂ physisorption isotherms showed a decline in the surface area and total pore volume of the zeolite because of the blocking of pores. The zeolite-Ni(H₂PO₄)₂ catalyst had higher acidity than unmodified zeolite and zeolite-Ni catalysts, which inherently suggested that the presence of phosphate groups results in higher catalytic activity toward isopropyl alcohol. The highest catalytic activity was attained by 8 mEq/g metal loading zeolite-Ni(H₂PO₄)₂ with isopropyl alcohol conversion of 81.51%, diisopropyl ether yield, and selectivity of 40.77 and 33.16%. The reusability study suggested that the zeolite-Ni(H₂PO₄)₂ catalyst was still active and had sufficient catalytic activity stability toward isopropyl alcohol after the third cycle was reused. This nickel phosphate-based modified zeolite was adequately potential for diisopropyl ether production through isopropyl alcohol dehydration.

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.

Direct Transformation of Glycerol to Propanal using Zirconium Phosphate-Supported Bimetallic Catalysts

Selective transformation of glycerol to propanal (PA) provides a feasible route towards the sustainable synthesis of high value-added chemicals. In this work, zirconium phosphate (ZrP) was studied as support and Ru and Co as metal sites for glycerol hydrogenolysis in a continuous-flow reactor. It was found that ZrP-supported Co-O species had a moderate selectivity to PA (49.5 %) in glycerol hydrogenolysis. Notably, once Ru species were doped into CoO/ZrP, the resulting catalyst exhibited not only an outstanding catalytic performance for glycerol hydrogenolysis to PA (a selectivity of 80.2 % at full conversion), but also a high stability at least a 50 h long-term performance. The spent catalyst could be regenerated by calcining in air to remove carbonaceous deposits. Characterization indicated that the acid sites on ZrP played a very critical role in the dehydration of glycerol into acrolein (AE), that the distribution of Co was uniform, basically consistent with that of Zr, P and Ru, and that an especially close contact between Co-O and Ru species was formed on Ru/CoO/ZrP catalyst. The further activity tests and characterizations confirmed that there was a strong interaction between the dispersed Co-O species and Ru⁰ nanoparticles, which endowed Ru sites with high electronic density. This effect could play a role in facilitating the dissociation of H₂ , and thus in promoting the hydrogenation reaction. Besides, DFT calculations suggested that the Co-O species can adsorb more strongly the C=C bond of the intermediate AE on a highly coordinatively unsaturated Co (Co_cus ) site and thus lead to preferential hydrogenation at the C=C bond of AE to PA.

Influence of Dimethylsulfoxide and Dioxygen in the Fructose Conversion to 5-Hydroxymethylfurfural Mediated by Glycerol's Acidic Carbon

Both the catalytic production of 5-hydroxymethylfurfural (5-HMF) from carbohydrates and the use of a catalyst obtained from residues stand out for adding value to by-products and wastes. These processes contribute to the circular economy. In this work it was evaluated optimized conditions for 5-HMF production from fructose with high yield and selectivity. The reaction was catalyzed by an acidic carbon obtained from glycerol, a byproduct of the biodiesel industry. Special attention has been given to the use of dimethyl sulfoxide (DMSO) as a solvent and its influence on system activity, both in the presence and absence of O₂. Glycerol's carbon with acidic properties can be effectively used as catalyst in fructose dehydration, allowed achieving conversions close to 100% with 5-HMF selectivities higher than 90%. The catalyst can be reused in consecutive batch runs. The influence of DMSO in the presence of O₂ should be considered in the catalytic activity, as the stabilization of a reaction intermediate by the [O₂:DMSO] complex is favored and, both fructose conversion and 5-HMF yield increase.

Solvent-Free Production of Isosorbide from Sorbitol Catalyzed by a Polymeric Solid Acid

A series of polymeric solid acid catalysts (PDSF-x) is prepared by grafting strong electron-withdrawing groups (-SO₂ CF₃ ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor synthesized hydrothermally. The effect of acid strength on sorbitol dehydration is investigated. The textural properties, acidity, and hydrophobicity are characterized by using Brunauer-Emmett-Teller analysis, elemental analysis, and contact angle tests. The results of FTIR spectroscopy and X-ray photoelectron spectroscopy show that both -SO₃ H and -SO₂ CF₃ are grafted onto the polymer network. We used solid-state ³¹ P NMR spectroscopy to show that the acid strength of PDSF-x is enhanced significantly compared with that of PDS, especially for PDSF-0.05. As a result, PDSF-0.05 exhibits the highest isosorbide yield up to 80 %, a good turnover frequency of 231.5 h^-1 (compared to other catalysts), and excellent cyclic stability, which is attributed to its large specific surface area, appropriate acid strength, hydrophobicity, and stable framework structure. In addition, a plausible reaction pathway and kinetic analysis are proposed.