Solid Superacid Catalyst Research Articles

Glycerol Esterification to Glyceryl Diacetate over SO42−/W‐Zr Complex Solid Super Acid Catalysts

AbstractA series of SO42−/W−Zr catalysts with different W/Zr mole ratios were synthesized by solvent evaporation self‐assembly followed by impregnation of sulfuric acid. The catalysts were examined in the glycerol esterification with acetic acid, and fully characterized by XRD, BET, TEM, XPS, NH3‐TPD, H2O‐TPD and pyridine adsorption infrared spectroscopy. The results revealed that W/Zr mole ratio and calcination temperature significantly affected the structure, acidity and catalytic performance of the catalysts. SO42−/W−Zr(1:1)‐500 (with a W/Zr mole ratio of 1:1, calcined at 500 °C) exhibited the highest catalytic activity, which is mainly due to the fact that the catalyst had more acidic sites and good water tolerance. In addition, the catalyst also showed excellent recyclability, in five repeated runs the conversion of glycerol and yields of products remained stable.

Solvent Regeneration of a CO2-Loaded BEA–AMP Bi-Blend Amine Solvent with the Aid of a Solid Brønsted Ce(SO4)2/ZrO2 Superacid Catalyst

The objective of the current research is to investigate the addition of a solid proton donor catalyst such as HZSM-5 and Ce(SO4)2/ZrO2 to the amine solvent regeneration process at the operation temperature of 85 °C. The HZSM-5 zeolite with Si/Al ratios of 5 to 20 was synthesized by hydrothermal method. The solid superacid catalyst, Ce(SO4)2/ZrO2, was prepared by simply doping ZrO2 with Ce and modifying with sulfate simultaneously. Various techniques such as X-ray diffraction, energy-dispersive X-ray spectrometry, Brunauer―Emmett―Teller, NH3-temperature-programmed desorption, and pyridine Fourier transform infrared spectroscopy were used to characterize the solid acid catalysts. The performance of the catalysts was evaluated in terms of their CO2 desorption rate, CO2 cyclic capacity, and heat duty. The experimental results indicated that the addition of the catalyst to the solvent regeneration process showed simultaneous increase in CO2 desorption rate and cyclic capacity as well as reduction of heat duty....

Iron modified /ZrO2 in application of removing trace olefins from aromatics

A solid super-acid catalyst /Fe2O3-ZrO2 (FeSZ) was prepared by coprecipitation method to remove olefins from aromatics. Effects of iron sources and Fe2O3 content were studied. FeSZ and /ZrO2 (SZ) were characterized by XRD, FT-IR and NH3-TPD. The characterization of the catalysts revealed that the addition of iron purified the tetragonal phase of ZrO2, increased the strength of the acid sites. Catalytic activity test showed that FeSZ with 5 wt% Fe2O3, using Fe2 (SO4)3 as iron source, exhibited the highest activity for removal of olefins. Compared with SZ, the catalytic activity of FeSZ increased 6.1%.

Low Temperature Direct Conversion of Methane using a Solid Superacid

AbstractThe direct conversion of methane to higher hydrocarbons and hydrogen can be catalyzed using “superacids”: nCH4→CnHm+xH2. The first report of catalytic oligomerization of methane using superacids was that of Olah et al., who demonstrated the superacidity of FSO3H−SbF5, which is a liquid. More recently, Vasireddy et al. showed that gas‐phase HBr/AlBr3 was an active superacid. The only reported solid superacid for methane oligomerization is sulfated zirconia (SZ). Here, we report a new class of Br‐based solid superacids, AlBrx/H‐ZSM‐5 (“ABZ‐5”, x=1 or 2). ABZ‐5 is based on gas‐phase HBr/AlBr3, with the objective of synthesizing a heterogeneous analogue of the gas‐phase superacid HBr/AlBr3. The results show that ABZ‐5 is significantly more active than SZ. Perhaps more significantly, results here show methane conversions of ∼1 % at 300 °C using ABZ‐5. By comparison with SZ, 350 °C is the lowest temperature reported in the literature at which measurable conversions are shown, and the corresponding methane conversions were <0.15. Here, we demonstrate direct conversion of methane using a solid superacid catalyst, AlBrx/H‐ZSM‐5. This solid catalyst is synthesized using a vapor‐phase process in which AlBr3 vapor is grafted on to solid H‐SZM‐5. This catalyst is characterized using NH3‐TPD, XRD, and DRIFTS. Hydrocarbon products observed in the temperature range of 200–400 °C include both C2–C6 hydrocarbons and aromatics.

Preparation of Solid Superacid Catalysts and Oil Oxidative Desulfurization Using K2FeO4

A $$\rm{SO_4^{2-}}$$ /MCM-41 superacid catalyst was prepared by impregnation and characterized by various methods. A novel procedure for oxidative desulfurization of simulated light fuel oil using K2FeO4 over $$\rm{SO_4^{2-}}$$ /MCM-41 was developed. Fourier transform infrared spectroscopy (FTIR) and low-angle X-ray diffractometry (XRD) show that the material synthesized by the precipitation-sol-hydrothermal method is mobil composition of matter no. 41 (MCM-41). Thermogravimetry/differential thermal analysis (TG-DTA) shows that when the calcination temperature is higher than 300°.

Biodiesel from Hydrolyzed Waste Cooking Oil Using a S-ZrO2/SBA-15 Super Acid Catalyst under Sub-Critical Conditions

Due to rapid changes in food habits, a substantial amount of waste fat and used oils are generated each year. Due to strong policies, the disposal of this material into nearby sewers causes ecological and environmental problems in many parts of the world. For efficient management, waste cooking oil, a less expensive, alternative and promising feedstock, can be used as a raw material for producing biofuel. In the present study, we produced a biodiesel from hydrolyzed waste cooking oil with a subcritical methanol process using a synthesized solid super acid catalyst, a sulfated zirconium oxide supported on Santa Barbara Amorphous silica (S-ZrO2/SBA-15). The characterization of the synthesized catalyst was carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), and the Brunauer-Emmett-Teller (BET) method. The catalytic effect on biodiesel production was examined by varying the parameters: temperatures of 120 to 200 °C, 5–20 min times, oil-to-methanol mole ratios between 1:5 to 1:20, and catalyst loadings of 1–2.5%. The maximum biodiesel yield was 96.383%, obtained under optimum reaction conditions of 140 °C, 10 min, and a 1:10 oil-to-methanol molar ratio with a 2.0% catalyst loading. We successfully reused the catalyst five times without regeneration with a 90% efficiency. The fuel properties were found to be within the limits set by the biodiesel standard.

Synthesis of SO4 2−/Zr-silicalite-1 zeolite catalysts for upgrading and visbreaking of heavy oil

Catalyst is crucially important to reduce the viscosity of heavy oil during the catalytic aquathermolysis. SO4 2−-modified ZrO2-based nanoparticle catalyst is a commonly used catalyst. But less acid sites and poor hydrothermal stability limited further improving its catalytic performance and practical application. In this study, the Zr-doped silicalite zeolite catalysts with large surface area were prepared as a support matrix, and SO4 2−-modified Zr-doped silicalite zeolite (denoted as SO4 2−/Zr-silicalite-1 zeolite) was used as a solid superacid catalyst to crack the heavy oil. A reference catalyst of SO4 2−/Zr-SiO2 nanoparticles (NPs) was also prepared, which has the same composition with the SO4 2−/Zr-silicalite-1 zeolite catalyst. Compared with the SO4 2−/Zr-SiO2 NP catalyst, the amount of acid sites for the SO4 2−/Zr-silicalite-1 zeolite catalyst is significantly increased and the viscosity reduction efficiency is also enhanced by 40%. More importantly, the SO4 2−/Zr-silicalite-1 zeolite catalyst exhibits a high hydrothermal stability. After catalytic aquathermolysis, the quality of the heavy oil was also ameliorated. The heavy resins and asphaltenes reduced, while the light saturated and aromatic hydrocarbon increased. The results suggest metal element-doped silicalite zeolite catalyst is a potential useful way to solving the less acid sites and poor hydrothermal stability for the SO4 2−-modified nanoparticle catalyst.

Production of Dibutyl Maleate with SO42-/Fe2O3 Solid Acid Catalyst

This paper explores the impact of catalyst dosage, molar ratio of normal butanol to maleic anhydride, reaction temperature and reaction time, etc. on esterification rate in combination with the synthesis of dibutyl maleate with SO42-/Fe2O3 solid super acid catalyst prepared with ferrous sulfate, a by-product to produce titanium dioxide. It turned out that the preferable conditions for the synthesis of dibutyl maleate with SO42-/Fe2O3 solid super acid catalyst are as follows: catalyst dosage accounting for 2.0% of the amount of reactive material, molar ratio of alcohol to acid of 3.5:1, reaction temperature of 120°C and reaction time of 3h. Under the preferable conditions, the esterification rate of normal butanol to maleic anhydride can reach 90% in esterification reaction. The infrared spectroscopy shows that the synthetic dibutyl maleate conforms to the standard diagram.

Reusable and efficient polyvinylpolypyrrolidone-supported triflic acid catalyst for acylation of alcohols, phenols, amines, and thiols under solvent-free conditions

A triflic acid-functionalized polyvinylpolypyrrolidone was prepared and fully characterized by FT-IR, TGA, and SEM. This super acidic solid catalyst shows high catalytic activity for selective acylation of alcohols, phenols, amines, and thiols with anhydrides under solvent-free conditions at room temperature. In addition, this method features an easy to handle solid super acid catalyst and an operationally simple procedure, affording the desired acylated products in excellent yields.

The supported sulphated La2O3-ZrO2 on SBA-15 as a promising mesoporous solid superacid catalyst for alkenylation of p-xylene with phenylacetylene

The well-dispersed supported sulphated La2O3-ZrO2 (SLZ) superacid catalysts on SBA-15 with loadings were prepared and applied in alkenylation of p-xylene with phenylacetylene. The amount of acidic sites increases with the enlarged loading, it reaches maximum at the loading of 25%, and then decreases while the loading is further increased. The increasing loading leads to a continuous decrease in specific surface area and pore volume. The optimized 25% SLZ/SBA-15 catalyst shows the outstanding catalytic performance, attributed to the more acidic sites and the not too low surface area and pore volume. The developed well-ordered mesoporous sulphated La2O3-ZrO2 solid superacid catalyst may be extended to diverse transformations.

Comparison of Ni-S2O82–/ZrO2–Al2O3 Catalysts prepared by Microemulsion and Impregnation Methods and their Performance for Isomerisation

Bifunctional Ni-S2O82–/ZrO2–Al2O3 (Ni-SSZA) solid superacid catalysts were prepared by microemulsion (Ni-SSZA-M) and impregnation (Ni-SSZA-I) methods and their performance for n-pentane isomerisation was studied. The catalysts were characterised by BET, XPS, XRD, FTIR, Py–FTIR, TPR, TEM and CO uptake. The results show that, compared with the Ni-SSZA-I catalyst, the Ni-SSZA-M catalyst shows smaller and more uniform Ni particles, higher surface area, smaller crystallite size of tetragonal ZrO2, more metal active sites and stronger acidity. The activity test indicated that loading Ni by the microemulsion method can significantly improve the isomerisation activity of the catalyst at lower reaction temperatures. In comparison with the Ni-SSZA-I catalyst, the isopentane yield for Ni-SSZA-M was improved by 11.6% and the optimum temperature was decreased by 60 °C.

ChemInform Abstract: Efficient Biodiesel Production via Solid Superacid Catalysis: A Critical Review on Recent Breakthrough

AbstractReview: 141 refs.

Enzymatic Pretreatment Coupled with the Addition of p-Hydroxyanisole Increased Levulinic Acid Production from Steam-Exploded Rice Straw Short Fiber

Levulinic acid production, directly from lignocellulosic biomass, resulted in low yields due to the poor substrate accessibility and occurrence of side reactions. The effects of reaction conditions, enzymatic pretreatment, and inhibitor addition on the conversion of steam-exploded rice straw (SERS) short fiber to levulinic acid catalyzed by solid superacid were investigated systematically. The results indicated that the optimal reaction conditions were temperature, time, and solid superacid concentration combinations of 200°C, 15min, and 7.5%. Enzymatic pretreatment improved the substrate accessibility to solid superacid catalyst, and p-hydroxyanisole inhibitor reduced the side reactions during reaction processes, which helped to increase levulinic acid yield. The levulinic acid yield reached 25.2% under the optimal conditions, which was 61.5% higher than that without enzymatic pretreatment and inhibitor addition. Therefore, enzymatic pretreatment coupled with the addition of p-hydroxyanisole increased levulinic acid production effectively, which contributed to the value-added utilization of lignocellulosic biomass.

Study on the Preparation and Catalytic Activities of SO4 2− Promoted Metal Oxide Solid Superacid Catalysts for Model Oil Desulfurization

A series of SO4 2− promoted metal oxide solid superacids: SO4 2−/ZrO2–WO3 (SZW), SO4 2−/ZrO2–MoO3 (SZM) and SO4 2−/ZrO2–Cr2O3 (SZC) were prepared by incorporating different metals into SO4 2−/ZrO2 (SZ). The above four catalysts were characterized by Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction and NH3-temperature programmed desorption techniques and scanning electron microscope. Then, they were respectively used as catalysts for oxidative desulfurization for model oil under the same mild conditions. The results exhibited that catalytic activities of SZW, SZM and SZC all increased to different degrees compared with SZ. Among them SZC performed best. Finally, the possible mechanism of this reaction was also presented.

Heterogeneously-acid catalyzed oligomerization of glycerol over recyclable superacid Aquivion® PFSA

This manuscript explores the catalytic activity, selectivity and stability of Aquivion® PFSA PW98 in the oligomerization of glycerol. Aquivion® PFSA PW98 is a solid superacid catalyst with a Hammett acidity function of −12. Furthermore, the perfluorinated structure allows this polymer to stand quite high operating temperature (up to 150–160°C) without loss in mechanical and chemical integrity which is of huge interest for glycerol conversion. In this context, we discovered that Aquivion® PFSA PW98 was nearly fully selective to oligoglycerols up to 80% conversion of glycerol. The oligomerization degree of oligoglycerol and the regioselectivity of the reaction (linear vs branched and cyclic isomers) were fully analyzed by means of GC and SEC chromatographies. In contrast to conventional solid acid catalysts, Aquivion® PFSA PW98 was found highly robust in glycerol and was sucessfully recycled at least 10 times without apparent decrease in activity or selectivity. A comparison with Nafion NR 50 is also included to shed light on the potential of Aquivion® PFSA PW98 for acid-catalyzed conversion of glycerol.

A ternary nanooxide NiO-TiO2-ZrO2/SO42− as efficient solid superacid catalysts for electro-oxidation of glucose

A ternary composite of NiO and TiO2-ZrO2/SO42− solid superacid were synthesized and investigated as efficient anode catalysts for glucose electrooxidation. From X-ray diffraction (XRD) and scanning electron microscope (SEM), the precursors were found to convert into corresponding nanooxides. They were well dispersed with a size of approximate 70nm. The nanostructure was also analyzed by fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed that NiO-TiO2-ZrO2 nanooxides were modified by SO42− and solid superacid NiO-TiO2-ZrO2/SO42− have been synthesized. The electrochemical measurements indicated that, compared with NiO, the current density of NiO-TiO2-ZrO2/SO42− modified GC electrode increased 27% in 0.1M NaOH solution with 10mM glucose. Moreover, the kinetic results showed that the glucose electrooxidation on NiO-TiO2-ZrO2/SO42− is a surface controlling process. In a word, NiO-TiO2-ZrO2/SO42− nanoparticles possessed high catalytic activity and good stability in alkaline medium for glucose oxidation reaction (GOR).

Mild synthesis of biofuel over a microcrystalline S2O82 −/ZrO2 catalyst

A solid super acid catalyst, S2O82−/ZrO2, was prepared by a new synthesis route of one-pot method with ammonium persulfate via vapor phase hydrolysis to improve biodiesel production using expired soybean oil as reactant. Catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and NH3-temperature programmed desorption (NH3-TPD) to determine the optimum pretreatment conditions and understand the role of the active sites for transesterification. S2O82−/ZrO2 calcined at 500°C, which showed an amorphous phase by XRD characterization, was identified as composed of tetragonal phase ZrO2 microcrystallites by TEM examination. The microcrystallites which anchored more S2O82− had abundant super acid and displayed high catalytic activity in the transesterification under mild reaction conditions. The reaction parameters over the catalyst were optimized and both the conversion of soybean oil and selectivity of biofuel reached 100% under the conditions of 110°C of reaction temperature, 4h of reaction time and 20:1 of methanol to oil molar ratio. Moreover, the catalyst showed high stability in the reactions and no sulfur leaching was found in the biodiesel products in cyclic utilization.

Synthesis of Ethyl Levulinate from Levulinic Acid over Solid Super Acid Catalyst

In this study, 40 % H3PW12O40/ZrO2 catalyst was synthesized, characterized and tested for conversion of levulinic acid (LA) and ethanol (EtOH) to ethyl levulinate (EL). The catalyst was prepared through wetimpregnation method. Catalyst characterization using BET and NH3-TPD revealed that the catalytic performance was dominantly influenced by the acid sites and surface area of the catalyst. The perfomance of the catalyst was tested based on reaction time (30 min to 4 h) and reaction temperature (120 °C to 160 °C) with 1:5 levulinic acid to ethanol ratio. The 40 % H3PW12O40/ZrO2 catalyst exhibited high catalytic performance at 150 °C with time taken 3 h for 99 % yield of ethyl levulinate.

ChemInform Abstract: Taming of Superacids: PVP‐Triflic Acid as an Effective Solid Triflic Acid Equivalent for Friedel—Crafts Hydroxyalkylation and Acylation.

Abstract The application of poly(4-vinylpyridine) supported trifluoromethanesulfonic acid (PVP-TfOH, 1:10) as a convenient solid superacid catalyst system in Friedel–Crafts reactions is described. In the presence of PVP-TfOH, one pot solvent-free synthesis of a wide variety of diarylacetic acid derivatives was achieved by Friedel–Crafts hydroxyalkylation reaction of glyoxylic acid with arenes under mild conditions. Acylation of both activated and deactivated aromatic compounds with acetyl chloride was also achieved using PVP-TfOH complex under solvent-free conditions at room temperature. As the polymer supported triflic acid was found to be a very efficient and an easy-to-handle solid acid, it can be a useful addition to environmentally more adaptable strong acid catalyst systems.

Selective conversion of cotton cellulose to glucose and 5-hydroxymethyl furfural with SO42−/MxOy solid superacid catalyst

This paper presented a mild hydrothermal process for degradation of cotton cellulose with solid superacid catalyst and selective conversion of cotton cellulose to glucose and 5-hydroxymethyl furfural (HMF). Five kinds of solid superacid catalyst such as SO42−/SnO2, SO42−/TiO2, SO42−/ZrO2, SO42−/Fe2O3 and SO42−/Al2O3 were prepared by impregnation method. The BET surface area of catalyst SO42−/SnO2 was up to 118.8m2g−1 when impregnation was performed with 1molL−1 H2SO4 of impregnating solution at 550°C calcination temperature for 3h. It made the hydrothermal temperature of cellulose degradation decrease to 190°C successfully and suppressed the side reaction. The NH3-TPD profile of SO42−/SnO2 indicated there was a wide region of stronger acid sites on the catalyst surface. The depolymerization of cotton cellulose obtained 11.0% yield and 22.0% selectivity of HMF and 26.8% yield and 53.4% selectivity of glucose, respectively. The regeneration and reuse of solid superacid catalyst were also discussed in this paper.