Sulfated Zirconia Catalysts Research Articles

CONVERSİON OF n-HEXANE OVER CATALYSTS BASED ON SULFATED ZIRCONIUM DIOXIDE

The isomerization process is becoming increasingly important in the modern petroleum refining context due to the limitations on the content of benzene, aromatic compounds, and olefins in gasoline. Isomerization is an effective and profitable process for octane enhancement of gasoline unlike other octane increasing processes. Due to the low sulfur and benzene content, the isomerate can be used as an ideal blending gasoline component. Therefore, the isomerization process has a great importance in petroleum refineries to increase the fuel octane number. This article aimed to study the conversion process of normal hexane over palladium and platinum containing catalysts on the base of sulfated zirconium dioxide. It has been determined that due to their high-performance characteristics, catalytic systems based on sulfated zirconium dioxide can be considered the most promising for isomerization of normal alkanes. Moreover, comparison of palladium-containing catalysts based on sulfated zirconium dioxide with platinum-containing catalysts based on sulfated zirconium dioxide showed that palladium sulfated zirconia catalysts have high catalytic performance in the isomerization of normal hexane. Keywords: alkanes, catalyst, platinum, palladium, isomerization, temperature, sulfated zirconium dioxide. .

A novel method for synthesis of nonylated diphenylamine by alkylation of diphenylamine with nonene over Fe-promoted SO42-/ZrO2 catalysts

As a green and efficient antioxidant, nonylated diphenylamine (NDPA) is of great significance to fields such as lubricants, synthetic rubber, and plastic. However, traditional catalysts for synthesizing NDPA still exhibit drawbacks of low efficiency, equipment corrosion, non-renewability, and environmental pollution. To overcome these challenges, a series of Fe-promoted SO42-/ZrO2 catalysts were successfully developed and employed for the first time in the alkylation of DPA and NON to synthesize NDPA in our present work. Both synthesis variables of catalysts and reaction conditions were well optimized. The as-synthesized NFe2.50S1.0Z catalyst possessed excellent catalytic performance with a high yield of mono- and di-nonyl-diphenylamine, as well as better reusability and stability than activated clay. After 5 reaction cycles, over 90 % of the catalytic activity could be recovered by the thermal treatment. These observations make the Fe-promoted SO42-/ZrO2 catalyst a promising candidate for industrials. Additionally, to systematically investigate and elucidate the promoting effects of Fe on sulfated zirconia catalysts, a thorough characterization of the physicochemical properties of these catalysts was conducted through various techniques, including XRD, SEM, TEM equipped with EDX, N2 adsorption-desorption isotherms, EA, ICP-OES, FT-IR, XPS, and NH3-TPD. The results indicated that the introduction of a small amount of Fe into the catalyst promoted the stabilization of T-ZrO2, smaller grain sizes, increased specific surface area, and strong acidity, which in turn positively affected the catalytic performance. In addition, a possible reaction mechanism of Fe-promoted SO42-/ZrO2 catalyst for catalyzing the alkylation of DPA with NON was proposed.

Copper-induced formation of Lewis acid sites enhancing sulfated zirconia catalyzed i-butane normalization

Sulfated zirconia (SO42-/ZrO2) has been reported as an efficient and stable solid superacid catalyst for normalizing i-butane to n-butane, and may potentially substitute Pt-based catalysts. In this work, sulfated zirconia with Cu addition (Cu-SO42-/ZrO2) is prepared through a one-step method and exhibits comparable performance to commercial Pt-Cl/Al2O3, with an i-butane average conversion of 43.8% and n-butane average selectivity as high as 86.1%, while maintaining a stable n-butane yield for up to 120 hours. The relationship between Cu-promoter-induced physicochemical properties and catalytic performance for sulfated zirconia catalysts is investigated in detail, with the help of XPS, NH3-TPD, pyridine-IR, and density functional theory calculation. A volcano-type relationship is found between Cu content and n-butane yield, where n-butane yield first increases from 32.23% to 37.71%, and then decreases to 29.56%, with the gradual increase of Cu content. The moderate Cu species additive is beneficial to release Zr Lewis acid site from sulfate and increase its Lewis acid density, which accounts for its excellent catalytic selectivity for i-butane normalization. The excess Cu promoter covers the exposed Zr Lewis active sites, leading to the decayed i-butane conversion. Therefore, Lewis active sites density is regarded as descriptor to corelate n-butane yield, accounting for the volcano relationship between Cu content and n-butane yield for Cu-SO42-/ZrO2. This work demonstrates the feasibility of Cu modification and provides insight into the promotion mechanism, which may be extended to other solid superacid catalysts beyond sulfated zirconia.

Preparation of Solid Superacid SO42-/ZrO2 and SO42-/ZrO2-MxOy (M=Ce, Co, Mn, and Zn) and Its Application in Toluene Nitration.

The nitration reaction of aromatic compounds is one of the extensively studied chemical reactions that result in the manufacturing of various industrial products applied in pharmaceuticals, dyes, perfumes, and explosives. A series of modified sulfated zirconia (SZ) catalysts SO42-/ZrO2-MxOy (M=Ce, Co, Mn, Zn, and M/SZ) doped with different metal elements by a coprecipitation method were investigated in the toluene nitration reaction. Various characterization techniques (X-ray diffraction, Brunauer-Emmett-Teller, thermogravimetric analysis, X-ray photoelectron spectroscopy, and temperature-programmed desorption of ammonia) indicated that doping metal elements in SZ led to excellent catalytic properties, increasing the specific surface area of the catalyst and facilitating the formation of a stable tetragonal zirconia phase. Doping zinc and cobalt in SZ enhanced the acidity of the catalyst and formed stronger acidic sites, promoting the generation of nitronium ions and providing more active sites for the toluene nitration reaction. Additionally, it reduced the loss of sulfate ions in the catalytic system that helped in improving the stability of the catalyst. Under the same conditions, the catalytic activity of toluene nitration reaction demonstrated the following order: Zn/SZ > Ce/SZ > Co/SZ > Mn/SZ > SZ, with the zinc-doped SZ catalyst exhibiting the best catalytic performance, achieving a toluene conversion rate of 78.58% and a para/ortho nitrotoluene ratio of 0.67.

Silica- and Alumina-Supported Sulfated Zirconia Catalysts for Hexane Isomerization: Effect of the Support Nature

Silica- and Alumina-Supported Sulfated Zirconia Catalysts for Hexane Isomerization: Effect of the Support Nature

Production of high-carbon-number bio-aviation fuels from furans using sulfated zirconia and silica-alumina aerogel catalysts

Lignocellulose can help produce fuels in biorefineries through its fractionated components such as cellulose, hemicelluloses, and lignin. For instance, hemicellulose-derived xylose has been studied for obtaining petroleum-substituting fuels. Therefore, in this study, catalytic hydroalkylation/alkylation (HAA) of xylose-derived 2-methylfuran (2-MF) with butanal was targeted to selectively produce high-carbon-number diesel fuels. To that end, silica–alumina (SiAl) aerogels with different Si/Al ratios and a series of sulfated zirconia (SZ) compounds calcined at various temperatures were prepared as catalysts to overcome the limitations of conventional hazardous homogeneous acid catalysts. The activity of the SiAl catalysts in forming the desired HAA product, 5,5-bissylvylbutane (denoted as BB), was found to be directly related to the number of acid sites and acid density. Moreover, increasing the Si/Al molar ratio, which reduced the acid density and number of acid sites, led to lower 2-MF conversions and BB yields. The optimal 2-MF conversion and BB yield with the SiAl catalysts (67 % and 45 %, respectively) were achieved using a Si/Al ratio of 8:2 mol/mol. Furthermore, SZ calcined at 700 °C (denoted as SZ-700) exhibited the highest activity among the SZ catalysts (72 % 2-MF conversion, 63 % BB yield), despite having the fewest acid sites and lowest acid density. This was presumably because of the physical structure of SZ-700, which featured mixed monoclinic and tetragonal phases, many oxygen vacancies, and a large accessible external surface area, which facilitated the HAA reactions. Hydrogenation and hydrodeoxygenation (HDO) of BB were performed thereafter using Pd/C and Ru/SiO2–Al2O3 catalysts, respectively. The resulting deoxygenated hydrocarbons comprised 15.1 % light hydrocarbons (C4–C8) and 83.1 % heavier hydrocarbons (C9–C20). Simulated distillation analysis of the post-HDO product distribution indicated that the liquid-phase product contained 70 % high-carbon-number bio-aviation fuels.

Conversion of Neem Oil (Azadirachta indica) to Biodiesel over SBA-15 Supported Sulphated Zirconia Catalysts

Conversion of Neem Oil (Azadirachta indica) to Biodiesel over SBA-15 Supported Sulphated Zirconia Catalysts

Markedly Improved Catalytic Dehydration of Sorbitol to Isosorbide by Sol-Gel Sulfated Zirconia: A Quantitative Structure-Reactivity Study.

Isosorbide, a bicyclic C6 diol, has considerable value as a precursor for the production of bio-derived polymers. Current production of isosorbide from sorbitol utilizes homogeneous acid, commonly H2SO4, creating harmful waste and complicating separation. Thus, a heterogeneous acid catalyst capable of producing isosorbide from sorbitol in high yield under mild conditions would be desirable. Reported here is a quantitative investigation of the liquid-phase dehydration of neat sorbitol over sulfated zirconia (SZ) solid acid catalysts produced via sol-gel synthesis. The catalyst preparation allows for precise surface area control (morphology) and tunable catalytic activity. The S/Zr ratio (0.1-2.0) and calcination temperature (425-625 °C) were varied to evaluate their effects on morphology, acidity, and reaction kinetics and, as a result, to optimize the catalytic system for this transformation. With the optimal SZ catalyst, complete conversion of sorbitol occurred in <2 h under mild conditions to give isosorbide in 76% yield. Overall, the quantitative kinetics and structure-reactivity studies provided valuable insights into the parameters that govern product yields and SZ catalyst activity, central among these being the relative proportion of acid site types and Brønsted surface density.

Metal-promoted sulfated zirconia catalysts redox and acidic characteristics and their impact on n-butane isomerization

Metal-promoted sulfated zirconia catalysts redox and acidic characteristics and their impact on n-butane isomerization

Study on the Role of Hydrogen in n-Hexane Isomerization Over Pt Promoted Sulfated Zirconia Catalyst

Study on the Role of Hydrogen in n-Hexane Isomerization Over Pt Promoted Sulfated Zirconia Catalyst

Production of H2-Free Carbon Monoxide from Formic Acid Dehydration: The Catalytic Role of Acid Sites in Sulfated Zirconia.

The formic acid (CH2O2) decomposition over sulfated zirconia (SZ) catalysts prepared under different synthesis conditions, such as calcination temperature (500–650 °C) and sulfate loading (0–20 wt.%), was investigated. Three sulfate species (tridentate, bridging bidentate, and pyrosulfate) on the SZ catalysts were characterized by using temperature-programmed decomposition (TPDE), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The acidic properties of the SZ catalysts were investigated by the temperature-programmed desorption of iso-propanol (IPA-TPD) and pyridine-adsorbed infrared (Py-IR) spectroscopy and correlated with their catalytic properties in formic acid decomposition. The relative contributions of Brønsted and Lewis acid sites to the formic acid dehydration were compared, and optimal synthetic conditions, such as calcination temperature and sulfate loading, were proposed.

Nanocatalysts of Sulfated Zirconia and Calcium Oxide/Zirconia for Microwave-Assisted Biodiesel Synthesis from Castor Oil

Nanocatalysts of sulfated zirconia (SZ) and CaO/zirconia for microwave assisted-biodiesel synthesis from castor oil have been successfully prepared. The aim of the research was to determine the effectiveness and the selectivity of catalysts in biodiesel production. The sulfated zirconia catalyst was prepared by the wet impregnation method while the calcium oxide/zirconia catalyst was prepared through the wet impregnation by microwave-assisted method. The catalysts were used for the esterification and transesterification reaction with the highest acidity and the basicity value of 7.16 mmol NH3 g-1, 87.76 mmol HCl g-1, respectively. The acidity and basicity of the catalysts are directly related to the catalyst active site in the esterification and transesterification process. The results showed that catalyst 0.5 M SZ 500 and 1: 0.2 CaO/ZrO2 800 had excellent stability that can be seen from their high crystallinity and large surface area. The biodiesel products characterized by 1H-NMR, GC-MS and Bomb calorimeter also showed excellent results. After purification, 1H-NMR result shows the conversion of castor oil into methyl ester is close to 100%. This was supported by GC-MS where the highest area of methyl ester is 93.91% of methyl ricinoleate.

Synthesis of sulfated zirconia catalyst using sol–gel technique for alkane isomerization

Synthesis of sulfated zirconia catalyst using sol–gel technique for alkane isomerization

Polyoxymethylene dimethyl ethers synthesis from methanol and formaldehyde solution over one-pot synthesized spherical mesoporous sulfated zirconia

The synthesis of polyoxymethylene dimethyl ethers as an ideal diesel fuel additive is the current hot topic of modern petrochemical industry for their expedient properties in mitigating air pollutants emission during combustion. In this work, a series of spherical sulfated zirconia catalysts were prepared by a one-pot hydrothermal method assisted with surfactant cetyltrimethylammonium bromide (CTAB). The prepared sulfated zirconia catalysts were used to catalyze PODEn synthesis from methanol and formaldehyde solution. Various characterization (XRD, BET, SEM, TGA, NH3-TPD, FTIR, and Py-IR) were employed to elaborate the structure–activity relationship of the studied catalytic system. The results demonstrated that S/Zr molar ratio in precursor solution played an effective role on catalyst morphology and acidic properties, where the weak Brønsted acid sites and strong Lewis acid sites were favorable to the conversion of methanol and formation of long-chain PODEn, respectively. The reaction parameters such as catalyst amount, molar ratio of FA/MeOH, reaction time, temperature and pressure were optimized. The speculated reaction pathway for PODEn synthesis was proposed based on the synergy of Brønsted and Lewis acid sites, which suggested that Brønsted and Lewis acid sites might be advantageous to the activation of polyoxymethylene hemiformals [CH3(OCH2)nOH] and methylene glycol (HOCH2OH), respectively.

Vapor Phase Alkylation of Isomeric Cresols with Tert-Butyl Alcohol over Perlite Supported Sulfated Zirconia Catalyst

In the present study, perlite was thermally activated and then modified desirably to generate super acidity by loading different weight percentages of sulfated zirconia (SZ) via the two-step sol-gel method. As-prepared sulfated zirconia perlite (SZP) catalysts showed suitable catalytic potential in the vapor phase alkylation of o, m, and p-cresols with tert-butyl alcohol. The presence of crystalline phases in SZP catalysts was confirmed by XRD and FT-IR studies. TEM images revealed the nano size of the catalysts in the range of 9–25 nm. The presence of SZ on the surface of perlite was further confirmed by N2 adsorption–desorption, SEM, SEM-EDX, TGA, and UV-Vis DRS techniques. The pyridine FT-IR results confirmed the existence of Brønsted, Lewis acidic sites and their combination as super acidic catalytic active centers on the surface of catalyst utilized in the vapor phase alkylation of o, m, and p-cresols with tert-butyl alcohol. The regeneration and reusability of the preferred catalyst until the 5th reaction cycle without any considerable loss in catalytic activity demonstrated the stability of the catalyst. Comparative studies show that SZP can be regenerated and is superior compared to other catalysts previously used for other alkylation reactions with the potential for use on a large scale.

Synthesis and Characterization of Sulfated Zirconia Catalyst for Light Naphtha Isomerization Process

The platinum-loaded zirconium oxide (Pt/SO4-2/ZrO2) catalyst was developed for the light naphtha atoms over the reaction temperature range of 160 to 220 °C, 1 and 3 h-1 LSHV and 10 bar. Platinum improved the stability of the catalyst by preventing the formation of a coke precursor at the strong acid site of sulfur zirconium. The acidity of the catalyst was characterized by of NH3-TPD and the effect of sulfur and calcination temperature on the surface area of ​​the final prepared zirconia was studied. The prepared catalyst shows high structural similar activity at temperature between 200 and 210°C for two types of light naphtha feed.

Nickel-modified sulfated zirconia catalyst: Synthesis and application for transforming waste cooking oil into biogasoline via a hydrocracking process

The synthesis of a sulfated zirconia catalyst and its modification with Ni metal was carried out and applied in the hydrocracking of waste cooking oil into biogasoline. The SO4/ZrO2 (SZ) catalyst was synthesized via a hydrothermal process using ZrOCl2·8H2O as a precursor, followed by sulfation using (NH4)2SO4 solution. The catalyst was calcined at a temperature of 600 °C. The obtained SZ catalyst was refluxed in aqueous solutions of Ni(NO3)2 with various Ni loadings (1, 2, and 3 wt% Ni), followed by reducing hydrogen gas at 400 °C to yield Ni/SZ catalysts. The impregnation of Ni on SO4/ZrO2 led to an increase in catalyst acidity, as well as their activity and selectivity for the hydrocracking process. Among ZrO2 and the synthesized catalysts, 1% Ni/SZ has the highest acidity level. The hydrocracking process was performed at 450 °C. The 1% Ni/SZ catalyst was able to selectively produce the gasoline fraction, with the conversion reaching 70.28% gasoline from 80.28% for the total liquid products. As a result, the catalyst was shown to be acceptable for industrial-scale applications.

The integrated reforming and isomerization of gasoline fractions for the production of eco-friendly motor gasolines

The paper reports data on the development and investigation of the advanced catalysts for reforming and isomerization of gasoline fractions, which were performed at the Center of New Chemical Technologies BIC SB RAS, particularly the commercial operation of the reforming catalyst PR-81. A new catalyst with an increased acidity, which provides a decrease in the content of aromatic hydrocarbons in reformate by 3–5 wt.%, was developed for the reforming of gasoline fractions. A new sulfated zirconia catalyst supported on the porous alumina matrix was devised for isomerization of the fraction of C5–C6 hydrocarbons. An efficient tungstated zirconia catalyst was suggested for isomerization of the fraction of C7 hydrocarbons. The indicated catalysts are employed in the proposed scheme of integrated reforming and isomerization processes, which ensures the production of motor gasolines Euro-5 and 6, as well as the promising gasolines with a decreased content of aromatic hydrocarbons.

Synthesis and Characterization of Ni-WO3/Sulfated Zirconia Nano catalyst for Isomerization of N-Hexane and Iraqi Light Naphtha

This work deals with preparation of Sulfated Zirconia catalyst (SZ) for isomerization of n-hexane model and refinery light naphtha, as well as enhanced the role of promoters to get the target with the mild condition, stability, and to prevent formation of coke precursors on strong acidic sites of the catalyst. The prepared SZ catalysts were characterization by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer –Emmett-Teller (BET) surface area analysis, Thermogravimetric Analysis (TGA), Scanning Electron Microscope (SEM) and atomic force microscopy (AFM) Analyzer. The results illustrate that the maximum conversion and selectivity for n-hexane isomerization with Ni-WSZ and operating temperature of 150 °C was 80.1% and 96 % respectively .Other set of experimental with light naphtha , the results show that the maximum conversion and selectivity with Ni-WSZ and operating temperature of 150 °C was 73.6% and 74% respectively.

Sulfated zirconia catalysts supported on mesoporous Mg-SBA-15 with different morphologies for highly efficient conversion of fructose to 5-hydroxymethylfurfural

In this work, the novel acid-base bi-functional mesoporous SBA-15 catalysts with four kinds of morphologies were synthesized by Mg incorporated and sulfated zirconia (SZ) grafted. The introduction of Mg to mesoporous SBA-15 materials significantly improves the strength of the base. And the supported SZ group exhibit effective Brønsted/Lewis acid strength. The physical and chemical properties of the prepared materials were systematically analyzed by the characterization tests of SEM, TEM, XRD, N 2 adsorption-desorption of, FT-IR, TGA, XPS, NH 3 /CO 2 -TPD and in-suit PY-IR. The obtained catalysts of SZ@Mg-SBA-15 could be applied to the fructose conversion into 5-hydroxymethylfurfural (5-HMF) with the co-solvent system of iPrOH/DMSO ( v / v = 9:1). 5-HMF was achieved under the optimal reaction condition with the highest yield of 98.6%. The result shows that the reaction of fructose dehydration into 5-HMF could be caused by the combination of Brønsted acid site and basic site. This work developed reaction system could avoid the large use of environmentally dangerous solvents, and provides a new economical and feasible method for the large-scale conversion of fructose biomass. • Mesoporous SZ@Mg-SBA-15 catalysts were successfully synthesized. • The acid-base bifunctional sites showed synergistic effects in catalytic activity. • The highest 5-HMF yields of 98.6% can be obtained from fructose. • The developed iPrOH/DMSO co-solvent has a minimal environmental impact. • The prepared catalyst can be reused without significant loss of activity.