Acidity Of Catalysts Research Articles

Acidic TiNb2O7 nanospheres supported with CeO2 to enhance NH3-SCR denitrification activity and resistance to H2O and SO2: Synergistic effect of CeO2 and TiNb2O7

TiNb2O7 material can be selected as the good support for NH3-SCR catalysts because of its shear structure and surface acidity. Increasing the acidity of catalyst is the key to achieving excellent NH3-SCR performance. In this work, m%CeO2/TiNb2O7 (m = 1, 2, 5, 8 and 10) catalysts were prepared by adjusting the Ce amount supported on TiNb2O7 with good acidity. Among them, 8%CeO2/TiNb2O7 exhibited good activity, N2 selectivity, and excellent SO2/H2O resistance. A series of analytical techniques were employed to examine the relationship among catalyst structure, surface properties and performance. The results show that the short-range ordered Cen+–O2--Nbn+ and Cen+–O2--Tin+ species from interactions between CeO2 and acidic support TiNb2O7 result in improved redox ability and acidity (especially Brønsted acids). The influence of SO2/H2O on SCR reaction and the reaction mechanism were researched using in-situ DRIFTS. The results indicate that SO2/H2O can promote NH3 adsorption and slightly inhibit NOx adsorption. The SCR reaction over 8%CeO2/TiNb2O7 mainly follows the E-R mechanism within the activation window, thus, the influence of SO2 and H2O on the reaction pathway is low, which probably contributes to the better tolerance against SO2 and H2O of the catalyst.

One factor at a time and two-factor optimization of transesterification parameters through central composite design (CCD) for the conversion of used peanut oil (UPNO) to biodiesel

This present investigation has optimized the acid and base catalysed transesterification process parameters to enhance the conversion of used peanut oil (UPNO) into biodiesel through a central composite design. Of the different acid and alkali catalysts tested, KOH and H2SO4 were found to be efficient catalysts, which yielded 94.2% UPNO biodiesel. For one factor at a time approach, four reaction parameters such as catalyst dose, reaction time, methanol volume, reaction temperature, and speed of mixing were chosen and a catalyst dose of 1 g and reaction time of 60 min was found to be an independent influential factor to enhance UPNO yield. Therefore, KOH/ H2SO4 catalyst concentration and reaction time were selected to ascertain their synergistic effect on the UPNO biodiesel production through central composite design (CCD). Two factorial CCD design unveils that 1.5 g catalyst (acid and alkali) and 90 min reaction time are the optimal conditions along with 70 °C reaction temperature, 6 mL methanol volume, and 50 rpm stirring speed for high UPNO biodiesel yield of 95.9%. In addition, the fatty acid profile of UPNO biodiesel contains oleic acid and linoleic acid as dominant fatty acids in the range of 55–56 % and 25–27%, respectively in KOH and H2SO4 catalysis. Further, MUFAs, PUFAs, and SFAs levels of UPNO biodiesel produced by H2SO4 catalyst were 55.44, 25.66 and 16.43 %, respectively while they were 56.12, 26.32 and 14.53%, respectively for KOH catalysis. Based on the results of high UPNO biodiesel and MUFA levels, it is contemplated that UPNO biodiesel could be a promising alternative fuel from a commercialization perspective.

Indium exchanged heteropoly tungstates: Efficient catalysts for the synthesis of glycerol carbonate from glycerol and urea

In this study, heteropoly tungstate protons were exchanged with various amounts of indium to impart Lewis acidity in Keggin heteropoly acid catalysts. The synthesis of glycerol carbonate from urea and glycerol was investigated using the synthesized InxTPA catalysts. The prepared catalysts were characterized by Fourier transforms infrared (FTIR), X-ray diffraction (XRD), Laser Raman, and temperature programmed desorption of ammonia studies. The obtained characterization results confirmed that the existence of Keggin ion structure of heteropoly acid after modification with indium ions. The modification of heteropoly tungstate with transition metal ions was found to improve its acidity and the stability of heteropoly acids (HPAs). The presence of Lewis acidic sites associated with the indium ions present in the catalyst was indicated by pyridine adsorbed FT-IR spectra. The amount of indium ions in heteropoly tungstate had an impact on the catalysts acidity, which in turn affected the activity of catalyst. The partially exchanged In0.66TPA catalyst demonstrated 69.4% glycerol conversion with 98.8% selectivity to glycerol carbonate. The study also investigated the impact of various reaction parameters such as reaction time, mole ratio of glycerol to urea, reaction temperature, and catalyst concentration and established the optimum reaction conditions.

Effect of Ⅲ B metals (Sc, Y, La and Ce) on active components regulation of VPO catalyst in n-butane selective oxidation

Vanadium phosphorus oxide (VPO) catalyst has been modified by the Ⅲ B elements (Sc, Y, La, Ce) have been prepared. Those catalysts were tested in n-butane selective oxidation, and it was shown that Y-VPO catalyst has the highest maleic anhydride (MA) yield among the studied catalysts. The VPO catalyst was characterized by a series of techniques. As evidenced by property characterization in conjunction with catalytic performance, we found that the presence of rare earth metals alters the phase composition of VPO catalyst. And then, the acidity of VPO catalyst was adjusted. Finally, the change of acidity could impact the n-butane activation process, which affected the n-butane conversion. Moreover, the rare earth metals also modulated the ratio of lattice oxygen and surface oxygen and then the MA selectivity.

Solid acid catalysts comprising heteropoly acids supported on SiO2, TiO2 and ZrO2: A microcalorimetric investigation of catalyst acidity and new insight into the mechanism of alcohol dehydration over HPA

Keggin-type heteropoly acids (HPAs) have strong Brønsted acidity and are widely used as acid catalysts. The aim of this work is the systematic characterisation of the acid strength of HPA catalysts comprising H3PW12O40 and H4SiW12O40 supported on SiO2, TiO2 and ZrO2 with 10–100% HPA loading and testing their activity in dehydration of alcohols to gain new mechanistic insight regarding the role of bulk-type and surface-type HPA catalysis in this reaction. The HPA catalysts were prepared by impregnation from an aqueous solution and characterised using BET, XRD, TGA, DRIFTS and ICP–OES. The acid strength of HPA catalysts was determined by NH3 adsorption microcalorimetry and found to decrease in the order HPA/SiO2 > HPA/TiO2 > HPA/ZrO2. For each type of HPA catalyst, the acid strength increased with increasing HPA loading. This can be attributed to HPA-support interaction reducing the strength of HPA proton sites at low HPA loadings. The activity of HPA catalysts was tested in the gas-phase dehydration of MeOH and i-PrOH in a fixed-bed reactor. Evidence was obtained that alcohol dehydration over HPA catalysts in a steady-state flow system occurs via the surface-type rather than bulk-type catalysis as suggested hitherto. This follows from a strong correlation between the reaction rate and the number of surface proton sites in HPA catalysts.

Zr-modified desilicated ZSM-5 catalysts as highly active and recyclable catalysts for production of biodiesel from soybean oil: Insight into improved catalyst properties, acidity and dispersion through desilication

Bio-based fuels, such as biodiesel, have recently gained attention due to concern about ever-increasing energy consumption and global warming. Solid catalysts are key materials in the production of green biodiesel. The use of solid catalysts in the production of biodiesel can lower the cost of the separation and thus reduce biodiesel costs. In the present study, zeolite-supported ZrO2 catalyst (ZrO2/ZSM-5) and a series of desilicated zeolite-supported ZrO2 catalyst [ZrO2/ZSM-5(0.1–0.3 M)] were successfully synthesized by impregnation method and used as new catalysts for the production of soybean oil biodiesel through transesterification. Desilication at various sodium hydroxide concentrations enhances the external surface area and mesoporous volume, without jeopardizing crystallinity or microporosity of the catalysts. The synthesized catalysts were characterized via X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), pyridine-FTIR, scanning electron microscopy, TEM, XRF, TGA and nitrogen adsorption-desorption. Nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC–MS) were used to characterize the biodiesel that was produced. The as-prepared ZrO2/ZSM-5(0.2 M) catalyst exhibited better catalytic activity in the transesterification of soybean oil with methanol, compared to ZrO2/ZSM-5 catalyst, due to large pore volume, high surface area, and high dispersion of ZrO2 on the desilicated zeolite support with improved acidity and high number of active sites. A biodiesel conversion of 90.1% and 97.84% were obtained for zeolite-supported ZrO2 catalyst and desilicated zeolite-supported ZrO2 catalyst, respectively, under optimum reaction conditions of 1.0 wt% catalyst loading, 1:16 soybean oil/methanol molar ratio at 200 °C in 4 h reaction time. Moreover, the desilicated zeolite-supported ZrO2 catalyst exhibited excellent stability and re-usability giving a biodiesel conversion of 93.8% after three cycles of reuse.

Hydro-co-processing of a jatropha oil and gas oil blend with a sulfided Ni–W catalyst supported on mesostructured materials Al(x)-SBA-15 type for cleaner hybrid diesel production: Effect of the Al/Si molar ratio

Obtaining cleaner hybrid diesel fractions by hydro-co-processing vegetable oil and gas oil blends requires tailoring intrinsic properties (metal content and acidity) of a solid catalyst. Such catalyst must promote the hydrodesulfurization (HDS), hydrodeoxygenation (HDO), and hydrocracking (HCK) reactions. In that sense, the present research work reports the synthesis (sol–gel and hydrothermal), characterization (N2 physisorption, XRD, HR-TEM, 27Al-MAS-NMR, Pyridine-FTIR, and RAMAN spectroscopy), and catalytic evaluation (6 MPa of H2 initial pressure, 360 °C, and 4 h) for Ni–W/Al(x)-SBA-15 sulfided catalysts during the hydroprocessing of a 20 vol% of Jatropha Curcas L. oil blend with a mixed gas oil (50 vol% LGO and 50 vol% HGO). Metal content of the catalysts was fixed at 2.5 wt% of NiO and 15 wt% of WO3, meanwhile, the Al/Si (x) molar ratio was adjusted in 0.1, 0.05, 0.033, 0.025, and 0.0 to study the effect of aluminum (Al) content during hydroprocessing. Liquid products were analyzed by FTIR, 1H NMR, ESI-MS, Simulated Distillation (ASTM D2887) and ASTM D4294 for S content. The effect of Al incorporation was mainly observed in the hydrotreating reactions (HDO and HDS) rather than HCK reactions. Intermediate Al/Si molar ratios (0.05, and 0.03) promoted the highest sulfur removal of about 13.1 % compared with the 10.7 % and 5.6 % for 0.1 and 0.025 Al/Si molar ratios, respectively. In addition, the highest content of Brønsted (0.05 mmol g−1) and Lewis (1.45 mmol g−1) acid sites was observed for the Ni–W/Al(0.05)-SBA-15 catalyst. Regarding HDO activity, it was the highest (57.3 %) for Ni–W/Al(0.1)-SBA-15 catalyst, and the lowest (30.9 %) for Ni–W/Al(0.025)-SBA-15, and Ni–W/Al(0.0)-SBA.15 sulfided catalysts. Finally, by comparing HDS and HCK activities of Ni–W/Al(0.05)-SBA-15 and Ni–W/Al(0.0)-SBA-15 sulfided catalysts, it was observed that HDS decreased 7.5 % and HCK increased 2.4 % when no Al was incorporated.

Investigation on site-specific tolerance to water for solid acid catalysts employed for a model reaction of solketal formation

The glycerol value addition by ketalization with acetone leads to solketal. Herein, we demonstrate the comparative efficiency of Brønsted and Lewis acid sites, using Hβ-zeolite & sulfated zirconia (SO42--ZrO2) as Brønsted and Lewis acid catalysts, respectively, for ketalization of glycerol to solketal. The catalysts were characterized using conventional techniques. Total acidity of both catalysts was ascertained with NH3-TPD. The sulfur content of SO42--ZrO2 was determined by CHNS analysis. The Brønsted/Lewis character of total acid sites for both catalysts was determined using FTIR of pyridine-Chemisorbed catalysts. Studies revealed that 5% (w/w) catalyst, 25 °C temperature and 2-hour reaction time were optimum parameters for Hβ-zeolite while, SO42--ZrO2 required 50 °C to match the performance. Hβ-zeolite exhibited higher selectivity at lower temperatures towards ketal and reusability without any performance drop upto 10 cycles. The performance-edge vis-à-vis reusability of catalysts indicated tolerance of Lewis acid sites towards hydration, where Hβ-zeolite outperforms SO42--ZrO2.

Chemical recycling of plastic waste to monomers: Effect of catalyst contact time, acidity and pore size on olefin recovery in ex-situ catalytic pyrolysis of polyolefin waste

The catalytic upgrading of post-consumer mixed polyolefinic waste pyrolysis vapors has been studied over five different solid acid catalysts to understand the effect of vapor-catalyst contact time and catalyst properties on the recovery of light olefins (C2-C4). HZSM-5 with Si/Al ratio of 11 and 27 produced the highest light olefins yields (83.4 wt% and 72.1 wt%, respectively) at a very short contact time of ∼5 ms while extending the contact time (≥23 ms) decreased the olefin yields and resulted in higher yields of aromatics (∼30.0 wt% and ∼40.0 wt%, respectively). Short contact time (5 ms) was not sufficient for HZSM-22 to crack pyrolysis vapors to C2-C4 olefins (8.0 wt%) but increasing contact time improved C2-C4 yields to 53.5 wt% without increased production of aromatics, which may be attributed to its small pore size (shape selectivity). SAPO-34, SAPO-11, and Al-MCM-41 were not selective to light olefins at any studied contact time.

Enhancement of Catalytic Activity on Crude Palm Oil Hydrocracking over SiO2/Zr Assisted with Potassium Hydrogen Phthalate.

In this study, the catalytic activity of bifunctional SiO2/Zr catalysts prepared by template and chelate methods using potassium hydrogen phthalate (KHF) for crude palm oil (CPO) hydrocracking to biofuels was investigated. The parent catalyst was successfully prepared by the sol-gel method, followed by the impregnation of zirconium using ZrOCl2·8H2O as a precursor. The morphological, structural, and textural properties of the catalysts were examined using several techniques, including electron microscopy energy-dispersive X-ray with mapping, transmission electron microscopy, X-ray diffraction, particle size analyzer (PSA), N2 adsorption-desorption, Fourier transform infrared-pyridine, and total and surface acidity analysis using the gravimetric method. The results showed that the physicochemical properties of SiO2/Zr were affected by different preparation methods. The template method assisted by KHF (SiO2/Zr-KHF2 and SiO2-KHF catalysts) provides a porous structure and high catalyst acidity. The catalyst prepared by the chelate method assisted by KHF (SiO2/Zr-KHF1) exhibited excellent Zr dispersion toward the SiO2 surface. The modification remarkably enhanced the catalytic activity of the parent catalyst in the order SiO2/Zr-KHF2 > SiO2/Zr-KHF1 > SiO2/Zr > SiO2-KHF > SiO2, with sufficient CPO conversion. The modified catalysts also suppressed coke formation and resulted in a high liquid yield. The catalyst features of SiO2/Zr-KHF1 promoted high-selectivity biofuel toward biogasoline, whereas SiO2/Zr-KHF2 led to an increase in the selectivity toward biojet. Reusability studies showed that the prepared catalysts were adequately stable over three consecutive runs for CPO conversion. Overall, SiO2/Zr prepared by the template method assisted by KHF was chosen as the most prominent catalyst for CPO hydrocracking.

Catalytic pyrolysis of microalgal lipids to liquid biofuels: Metal oxide doped catalysts with hierarchically porous structure and their performance

Catalytic pyrolysis of lipids is an alternative pathway for alternative aviation fuel production with advantages of H2-free and mild reaction conditions. However, it is still hindered by coking of catalysts and low selectivity of kerosene. In this research, composite catalysts were synthesized via postsynthesis method (alkali treatment) followed by doping of metal oxides (ZnO, La2O3, and CeO2). Catalytic performance of as-synthesized catalysts was evaluated during catalytic pyrolysis of microalgal lipids. The characterization of BET, XRD, SEM, NH3-TPD for catalysts indicated that alkaline treatment increased the mesoporous structure (5.28–5.91 nm) of microporous zeolite HZSM-5 to form a hierarchically porous structure without apparent disruption of crystal structure of zeolite, while doping of metal oxides (about 10 wt%) enhanced the performance of hetero-atoms (oxygen and nitrogen) removal. The acidity of as-synthesized catalysts significantly decreased from 1175.61 μmol/g (HZSM-5) to 406.77 μmol/g (Ce-MHZ). After catalytic pyrolysis carbon number distribution and compound type of produced liquid fuels tended to high kerosene components (above 40%) and increased hydrocarbon content with reduced content of oxygen-containing compounds. The hierarchically porous zeolite also presented aromatization for aromatic hydrocarbons in alternative aviation fuels. Catalytic mechanism was also elucidated including complex reactions of decarboxylation, decarbonylation, carbon chain cracking, and aromatization.

Hydrogen generation by hydrolysis of solid sodium borohydride for portable PEMFC applications

In this paper, the hydrogen generation by the hydrolysis of solid sodium borohydride was studied. A novel NiCoP/RC catalyst that loads Ni, Co, and P complexes on resin carbon (RC) was prepared to accelerate the hydrolysis. The hydrogen generation rate, reaction temperature, hydrogen output and water-hydrogen ratio during the reaction were recorded. In comparison to the commonly used cobalt chloride catalyst, the NiCoP/RC catalyst demonstrated superior catalytic activity. Citric acid was used to neutralize the alkaline by-products, and while the mixture of NiCoP/RC catalyst and citric acid increased the hydrogen output, it resulted in lower water utilization rate. Therefore, intermittent water feeding from the bottom of the reactor was proposed, which was found to be beneficial in terms of both hydrogen output and water utilization. Finally, the study warns about the potential for thermal runaway during the hydrolysis reaction of solid sodium borohydride.

Support Effect of Ga-Based Catalysts in the CO2-Assisted Oxidative Dehydrogenation of Propane

Carbon dioxide (CO2) assisted oxidative dehydrogenation of propane over Ga-modified catalysts is highly sensitive to the identity of support, but the underlying cause of support effects has not been well established. In this article, SSZ-13, SSZ-39, ZSM-5, silica and γ-Al2O3 were used to load Ga species by incipient wet impregnation. The structure, textural properties, acidity of the Ga-based catalysts and the process of CO2-assisted oxidative dehydrogenation of propane were examined by X-ray diffraction (XRD), nitrogen physisorption (N2 physisorption), ammonia temperature-programmed desorption (NH3-TPD), pyridine chemisorbed Fourier transform infrared spectra (Py-FTIR), OH-FTIR and in situ FTIR. Evaluation of the catalytic performance combined with detailed catalyst characterization suggests that their dehydrogenation activity is positively associated with the number of acid sites in middle strength, confirming that the Lewis acid sites generated by Ga cations are the active species in the reaction. Ga/Na-SSZ-39(9) also has feasible acidic strength and a unique channel structure, which is conducive to the dissociative adsorption of propane and desorption of olefins. The Ga/Na-SSZ-39(9) catalysts showed superior olefins selectivity and catalytic stability at 600 ℃ compared to any other catalysts. This approach to quantifying support acid strength, and channel structure and applying it as a key catalytic descriptor of support effects is a useful tool to enable the rational design of next-generation CO2-assisted oxidative dehydrogenation catalysts.

Hydrodeoxygenation of safflower oil over cobalt-doped metal oxide catalysts for bio-aviation fuel production

The catalytic hydrodeoxygenation process provides an alternative route for the production of renewable jet fuel, which can directly replace petroleum-derived hydrocarbons. To this end, the catalytic performance of Co-based catalysts supported by different metal oxides, γ-Al2O3, TiO2, ZnO and ZrO2 was tested to evaluate their catalytic activity and product selectivity in hydrodeoxygenation of safflower oil. The results indicated that catalytic performance changed in response to acidity, morphologies and particle size of catalysts. Benefiting from these combined characteristics, Co/ZnO catalyst exhibited a highly catalytic activity, being capable of producing jet fuel-range hydrocarbon selectivity of 65.96% under reaction parameters of 350 °C of reaction temperature, 8 h of reaction time and 75 bar of H2 initial pressure. In addition to superior activity, the coke content of Co/ZnO was much lower compared to other employed catalysts thereby affecting the stability of the catalyst and resulting in less deactivation and coke formation.

A catalyst acid property-included stoichiometric coefficient model for catalytic pyrolysis of hydrocarbon mixtures

Process modeling is considered an effective way to achieve refined management in the petrochemical industry, and is also the foundation and necessary link of intelligent chemical platform construction. This study aims to the simulation of the formation of gaseous products for the catalytic pyrolysis of representative naphtha compositions using a stoichiometric coefficient model. Firstly, the interaction mechanism of n/cyclo-paraffins was investigated using a pseudo-first-order kinetic model, and the cracking activity of hydrocarbon mixtures was quantified using the carbon number and cyclo-paraffin content. Subsequently, a database of the stoichiometric coefficients of the gaseous products was constructed. Considering the acid properties of the catalysts, a catalyst acid property-included stoichiometric coefficient model was developed to adapt to varying feedstock composition and catalyst systems, which could reflect gaseous production in the catalytic pyrolysis of multi-component mixed hydrocarbons. Moreover, the simulation using the present model shows that the production of light olefins in the catalytic pyrolysis of mixed hydrocarbons can be increased under the optimized catalyst acid properties. Hence, this study aims to provides theoretical guidance for the prediction of product distribution as well as the design and selection of catalysts used in the catalytic pyrolysis processes for multi-component mixed hydrocarbon.

Balance between Catalyst Acidity and Hydrophilicity in Biofuel Production from Fatty Acid Esterification over Al-SBA-15

A collection of Al-SBA-15 mesoporous catalysts (Si/Al = 13–174) was investigated to overcome typical accessibility constraints of microporous solids. 27Al MAS NMR confirmed the existence of tetrahedrally coordinated Al in the catalyst’s framework, and the fraction of such species increased as the Si/Al ratio decreased. Brønsted acidity followed the same pattern found using n-propylamine thermodecomposition. Mesoporous catalysts with lower Si/Al ratios exhibited a higher affinity to water as quantitatively determined using water adsorption experiments. Those surface properties were correlated to the catalytic performance on oleic acid esterification. The introduction of Al into the SBA-15 framework significantly improved esterification activity, leading to conversions ranging from 70 to 93%. This was explained by the acidity engendered upon Si substitution by Al. However, a turning point from which activity started dropping was registered and it was proposed to be associated with catalyst hydrophilicity. The balance between acidity and hydrophilicity was unveiled to be of paramount importance to accomplish the best catalytic efficiency and uppermost biofuel yield. Catalyst activity was also assessed for the esterification of stearic and linoleic acids. Higher conversion rates were accomplished with unsaturated fatty acids (oleic acid > linoleic acid > stearic acid) due to the higher reactivity of the carboxylic acid moieties as a consequence of the polarity of the double bonds in the carbon chain.

Optimization and modification of ZSM-5 zeolite for efficient catalytic cracking of 1,2-dichloroethane

The acidity and porosity of zeolite catalysts are crucial parameters affecting the catalytic performance. In this work, alkali treatment and metal species loading were used to modify the porosity and acidity of ZSM-5 zeolite to prepare an efficient catalyst for the 1,2-dichloroethane cracking reaction. After optimization, the highly active catalyst Zn (1%)/ZSM-5-120 was obtained, and 78% conversion of EDC and 99% selectivity toward VCM could be achieved under the conditions of 300 °C and 3.0 h−1 (WHSV). A detailed investigation was conducted on the effects of acidity, texture properties and metal species loaded on ZSM-5 zeolite on the 1,2-dichloroethane cracking reaction.

Boosting Higher Selectivity for Thymol Hydrogenation Reaction over Ni/Ce Catalyst

The production of menthol via thymol hydrogenation is an industrial technology but is challenging due to the unsatisfied selectivity to menthol. Herein, Ni/Ce catalysts were prepared and used in thymol hydrogenation. A high selectivity of menthol was achieved over Ni4/Ce1 catalysts under the optimized reaction condition. Ce incorporation can improve both the activity of Ni catalyst and the selectivity to menthol. To reveal the functions of Ce, catalyst characterizations were conducted. The catalytic activity improvement may be related to the remarkable increase in the surface area of the catalyst and the lower crystalline sizes of Ni that take place when a tiny amount of Ce is incorporated into Ni. Higher selectivity to menthol may be related to the modification of the acidity of an Ni catalyst. In addition, the stability of the Ni4/Ce1 catalysts was also evaluated, and after five recycles, the Ni4/Ce1 catalysts exhibited outstanding catalytic activity and stability.

Organic Structure-Directing Agent Free Synthesis of Mordenite with Seeds, Used as A Support for Mo Catalysts in the Transesterification of Soybean Oil

This work prepared mordenite using seeds and without organic structure-directing agents (OSDAs). The Mo/Mordenite was prepared through wet impregnation and the catalysts’ performance was checked for transesterification of soybean oil with methanol. The mordenite zeolite was prepared through hydrothermal crystallization under static conditions with a molar composition of 6Na<sub>2</sub>O:Al<sub>2</sub>O<sub>3</sub>:30SiO<sub>2</sub>:780H<sub>2</sub>O. The catalyst samples were characterized crystallinity through X-ray diffraction, elemental composition by X-ray fluorescence spectroscopy, Surface areas by N<sub>2</sub> adsorption-desorption, surface morphology scanning electron microscopy, functional group by infrared spectroscopy and active sites by temperature programmed desorption of ammonia. The transesterification of soybean oil was carried out using the following parameters: 5% catalyst by weight, 1:12 oil to methanol molar ratio, at 200°C for either 12 h or 24 h. X-ray diffraction patterns showed the characteristic peaks of the mordenite structure. After molybdenum oxide was added, the structure of mordenite zeolite was conserved while the specific surface area was reduced. The morphology can be described as a highly crystalline material with well-defined crystalline particles having a spherical profile characteristic of the typical morphology of sodium mordenite zeolite with a low silicon/aluminum ratio. The catalyst samples exhibited sites of a weak and medium-strength nature. The higher activity of the catalyst (Mo/Mordenite) about mordenite zeolite, could be justified by the existence of molybdenum. The wet impregnation of metal (Mo) on the surface of the MOR zeolite is an effective option to increase the acidity of the solid catalysts. Mordenite with 8.84% Mo could be a promising catalyst for the biodiesel factory.

TfOH-catalyzed direct Michael addition and cascade cyclization reactions of unactivated ketones: A divergent route to functionalized benzofurans and benzofuro[3,2-b]pyridines

TfOH-catalyzed direct Michael addition and cascade cyclization reactions of azadienes with unactivated ketones have been developed by controlling the amount of TfOH, which provide a divergent approach to 2,3-disubstituted benzofurans and benzofuro[3,2-b]pyridines. Due to their weak nucleophilicity, unactivated ketones are used for the first time to react with azadienes instead of preactivated carbonyl compounds, in which the catalyst acidity is a key parameter. This approach with commercial ketones in mild reaction conditions shows synthetic and environmentally benign advantages including metal-free catalyst, atom economy and simple operation.