Surface characterization and catalytic activity of sulfated tin oxide catalyst

Epoxidation of Argemone mexicana oil with peroxyacetic acid formed in-situ using sulfated tin (IV) oxide catalyst: Characterization; kinetic and thermodynamic analysis

In this study, sulfated tin (IV) oxide solid acid catalyst was prepared for the epoxidation of Argemone mexicana oil (AMO) with peroxyacetic acid formed in-situ. The catalyst was synthesized using the chemical co-precipitation method and characterized. The effects of various epoxidation parameters on ethylenic double bond conversion (%) and oxygen ring content were analyzed. The maximum ethylenic double bond conversion of 95.5% and epoxy oxygen content of 6.25 was found at the molar ratio of AMO to 30% of H₂O₂ = 1:2.5, molar ratio of AMO to acetic acid = 1:1.5, catalyst concentration = 12.5%, and reaction temperature = 70 °C at reaction time = 6 h. The kinetic and thermodynamic features of the epoxidation of AMO were also analyzed with appropriate models. The results of the kinetic study of the epoxidation reaction followed pseudo first order with the activation energy = 0.47.03 kJ/mol. Moreover, the thermodynamic constants of epoxidation of AMO were found as ΔH = 44.18 kJ/mol, ΔS = -137.91 Jmol^-1k^-1) and ΔG = 91.12 kJ/mol. The epoxidized product of AMO was further analyzed using FTIR, ¹H NMR, and ¹³C NMR. The results of these analyses confirmed the successful conversion of the ethylenic double bond in the AMO to EAMO.

Tuning the degradation activity and pathways of chlorinated organic pollutants over CeO2 catalyst with acid sites: synergistic effect of Lewis and Brønsted acid sites

The synergistic effect of Lewis and Brønsted acid sites can promote the effective degradation of chlorobenzene following the hydrolysis pathway of producing less toxic by-products.

Sulfamic acid incorporated HKUST-1: a highly active catalyst and efficient adsorbent

Herein we introduce an effective approach for incorporating sulfamic acid (SA) into HKUST-1. The synthesized materials have been characterized using XRD, XPS, BET, FT-IR, SEM, EDX and TEM. The X-ray diffraction pattern of SA@HKUST-1 is analogous to that of parent HKUST-1 in line shape and d-spacing, proving that chemical modification could be obtained without damage to structural solidity. The XPS spectra confirmed successful sulfonation, due to the single S 2p peak being attributable to SO₃H groups at 168 eV. Catalytic efficiency was studied for 7-hydroxy-4-methyl coumarin and 3,4-dihydropyrimidinone synthesis and it was found to be highly dependent on the amount of SA loaded over HKUST-1. Moreover, the adsorptive removal activity of some common organic and inorganic pollutants from water has been studied. To fully understand the adsorption process, the effects of initial dye concentration, pH of solution, adsorbent dosage, contact time and temperature on the adsorption process were successfully studied. Under the optimum conditions 10 wt% SA@HKUST-1 was able to reach the maximum adsorption capacity for Pb²⁺ (298 mg g⁻¹) and Malachite green (290 mg g⁻¹). Hopefully, this will facilitate research on improving the prospective use of MOFs for future applications.

Herein we introduce an effective approach for incorporating sulfamic acid (SA) into HKUST-1.

A sulfated/chlorinated Sr–Fe composite oxide as a novel solid and reusable superacid catalyst for oleic acid esterification

The high catalytic reactivity and reusability of the sulfated/chlorinated Sr–Fe oxide could be ascribed to the synergistic effect of coordinated Cl⁻ and surface SrSO₄ clusters on suppressing the chemisorption of oleic acid on the surface cations.

The catalytic combustion of CH2Cl2 over SO42−–TixSn1−x modified with Ru

Ru/SO₄²⁻–Ti_xSn_1−x presented high activity and selectivity due to the stable oxidization activity of Ru and super-strong acidity from SO₄²⁻.

Preparation and Characterization of Sulfonated Magnetic SiO2 Microspheres as the Solid Acid Catalysts for Esterification

The sulfonated magnetic SiO₂ microsphere solid acid catalysts were prepared by the impregnation and grafting methods with iron oxide magnetic nanoparticles (Fe₃O₄ MNPs) as the magnetic cores. The catalytic properties of the magnetic SiO₂ solid acid catalyst were studied in detail. The characterization results showed that the SiO₂ was successfully coated on the Fe₃O₄ MNPs. Compared with the grafting method, impregnated solid acid exhibits higher catalytic performance, which reached an esterification rate of up to 99.00% when the reaction temperature was 105 °C, the molar ratio of n-butanol/adipic acid was 3:1, and the ratio of the catalyst (the mass of magnetic solid acid) to liquids (the total volume of n-butanol and adipic acid) was 2.95%. The magnetic solid acid exhibited great separation ability and reusability. After six times of recycle, the conversion of the grafted magnetic solid acid still attained 85.61% compared with that of the impregnated magnetic solid acid, which reduced to 81.35%, holding great potential for green chemical processes.

The Effects of Exposed Specific Facets and Sulfation on the Surface Acidity of Cu2 O Solids

Cuprous oxide microcrystals with {111}, {111}/{100}, and {100} exposed facets were synthesized. ³¹ P MAS NMR using trimethylphosphine as the probe molecule was employed to study the acidic properties of samples. It was found that the total acidic density of samples increases evidently after sulfation compared with the pristine cuprous oxide microcrystals. During sulfation, new {100} facets are formed at the expense of {111} facets and lead to the generation of two Lewis acid sites due to the different binding states of SO₄ ^2- on {111} and {100} facets. Moreover, DFT calculation was used to illustrate the binding models of SO₄ ^2- on {111} and {100} facets. Also, a Pechmann condensation reaction was applied to study the acidic catalytic activity of these samples. It was found that the sulfated {111} facet has better activity due to its higher Lewis acid density compared with the sulfated {100} facet.

Nano-sized mesoporous phosphated tin oxide as an efficient solid acid catalyst

Herein, we prepared a mesoporous tin oxide catalyst (mSnO₂) activated with phosphate species by the adsorption of phosphate ions from a phosphoric acid solution onto tin oxyhydroxide (Sn(OH)₄) surface.

Efficient biodiesel production via solid superacid catalysis: a critical review on recent breakthrough

Biodiesel produced from triglycerides and/or free fatty acids (FFAs) by transesterification and esterification has attracted immense attention during the past decades as a biodegradable, renewable and sustainable fuel.

Synthesis of waste cooking oil based biodiesel via ferric-manganese promoted molybdenum oxide / zirconia nanoparticle solid acid catalyst: influence of ferric and manganese dopants

The utilization of ferric-manganese promoted molybdenum oxide/zirconia (Fe-Mn- MoO3/ZrO2) (FMMZ) solid acid catalyst for production of biodiesel was demonstrated. FMMZ is produced through impregnation reaction followed by calcination at 600°C for 3 h. The characterization of FMMZ had been done using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), temperature programmed desorption of NH3 (TPD-NH3), transmission electron microscopy(TEM) and Brunner-Emmett-Teller (BET) surface area measurement. The effect of waste cooking oil methyl esters (WCOME's) yield on the reactions variables such as reaction temperature, catalyst loading, molar ratio of methanol/oil and reusability were also assessed. The catalyst was used to convert the waste cooking oil into corresponding methyl esters (95.6%±0.15) within 5 h at 200℃ reaction temperature, 600 rpm stirring speed, 1:25 molar ratio of oil to alcohol and 4% w/w catalyst loading. The reported catalyst was successfully recycled in six connective experiments without loss in activity. Moreover, the fuel properties of WCOME's were also reported using ASTM D 6751 methods.

Facet-dependent acidic and catalytic properties of sulfated titania solid superacids

Sulfated titania solid superacids with different dominant facets were prepared and dominant {001} facets facilitated the enhancement of acidic properties.

Future of nano-/hierarchical zeolites in catalysis: gaseous phase or liquid phase system

This perspective highlights the catalytic characteristics and future prospects of nano-/hierarchical zeolites in gaseous phase and liquid phase reactions.

Facet-dependent acidic and catalytic properties of sulfated titania solid superacids

Sulfated titania solid superacids with different dominant facets were prepared and dominant {001} facets facilitated the enhancement of acidic properties.

Esterification of Free Fatty Acids in Crude Palm Oil Using Sulfated Cobalt–Tin Mixed Oxide Catalysts

In this study, sulfated tin oxide was modified with cobalt oxide resulting in sulfated cobalt–tin mixed oxide (SO42–/Co2O3–SnO2). For the first time, the catalytic activity of SO42–/Co2O3–SnO2 for the esterification reaction of free fatty acids (FFA) in crude palm oil to produce methyl esters has been investigated. The effects of amount of Co and calcination temperature were studied. The properties of SO42–/Co2O3–SnO2 were determined with N2 adsorption, X-ray diffraction and X-ray fluorescence analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and potentiometric titration. The esterification was carried out in a stirred-tank reactor equipped with a reflux condenser. The reaction conditions (methanol/oil ratio, catalyst size, catalyst loading and reaction time) were optimized. The results confirm that SO42–/Co2O3–SnO2 is a promising catalyst in the production of methyl esters from FFA in crude palm oil. The addition of Co improved the reusability of sulfated tin oxide.