SOLID BASE CATALYZED TRANSESTERIFICATION OF CANOLA OIL

Catalytic activities of synthesized solid base catalysts (alumina loaded with solution of different potassium compounds such as KI, KF, K₂CO₃, and KNO₃ with the loading amount of 35 wt.%) were tested for the transesterification reaction of canola oil with methanol and ethanol in a batch reactor in a temperature range of 25–60°C and different feed ratios of methanol/oil between 6:1 and 18:1. Synthesized KF/Al₂O₃ solid base catalyst showed the highest activity in the transesterification of canola oil with methanol and gave much stabler methyl ester content during the reaction with the highest yield of 99.6% at the end of the eight-hour reaction time at 60°C, with a methanol/oil ratio of 15:1 and a catalyst amount of 3 wt.%. Formation of K₂O phase and the formation of the surface Al-O-K groups by salt-support interactions were observed during the synthesis of the catalysts. Methanol was found to be much more reactive than ethanol in the transesterification reaction.     

Preparation of meso-structured silica–calcium mixed oxide (MSCMO) catalyst for converting Vietnamese rubber seed oil to biodiesel

This report covered some new contributions in catalyst preparation and characterization. Meso-structured silica–calcium mixed oxide catalyst possessed both acidic and basic sites was synthesized through co-condensation method in alkaline environment using tetraethylorthosilicate, CaO, and cetyltrimethylammoniumbromide. The co-condensation process was established at 90 °C for 24 h obtaining white-gel precipitate which was dried at 120 °C followed by calcination at 550 °C for 5 h. The as-synthesized catalyst was used in conversion of rich free fatty acid rubber seed oil (22 %wt) in Vietnam to fatty acid methyl esters (FAMEs) in mild conditions such as temperature of 120 °C, time of 4 h, catalyst dosage of 3 %wt, methanol/oil mass ratio of 2.5/1 and agitating speed of 550 rpm achieving the reaction yield of 95.4 %. The catalyst were characterized by various techniques such as X-ray diffraction, transmission electron spectroscopy, Nitrogen Adsorption–Desorption Analysis (BET), temperature programmed desorption (NH₃ and CO₂-TPD). Especially, X-ray absorption spectroscopies was applied to explain the occurrence of acid and base sites on catalysts surface. The analysis showed the sixfold coordinated calcium sites characterizing for the mixed oxide structure of CaO–SiO₂. The results helped to simulate the bonding structure around the Ca sites indicating the electrostatic charge differences along the Ca–O–Si connections and the ability for occurring the defect sites containing the O^2? moieties corresponding to the acidity and basicity of the catalysts respectively. Gas chromatography–mass spectroscopy was also used to determine the composition of the FAMEs showing high purity of these products.     

Calcium/chitosan spheres as catalyst for biodiesel production

Chitosan, an abundant biopolymer extracted from crustacean shells, can be used as a structuring agent by the insertion of calcium oxide and used as a catalyst in transesterification reactions. These calcium‐incorporated chitosan spheres were calcined in order to obtain a porous calcium catalyst without organic material. The materials were characterized using X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared and X‐ray photoelectron spectroscopies, temperature‐programmed desorption of CO₂, scanning electron microscopy and specific surface area analysis. Afterwards the calcined calcium/chitosan spheres were used in the transesterification reaction of sunflower oil with methanol. The conversion of sunflower oil to methyl esters (Y_FAME), under optimized reaction conditions, which were determined by factorial experimental design (X_MR, 1:9; X_CAT, 3 wt%; time, 4 h; temperature, 60 °C; magnetic stirring, 1000 rpm), was 56.12 ± 0.32 wt%. These results show that chitosan can be used as a precursor for the formation of calcium/chitosan spheres, yielding a porous calcium oxide (with higher surface area) that can be used as an alkaline catalyst for biodiesel production. © 2014 Society of Chemical Industry     

Sol–Gel Synthesis of MoO3/SiO2 Composite for Catalytic Application in Condensation of Anisole with Paraformaldehyde

MoO₃/SiO₂ composite with varying amounts of MoO₃ loading (1–20 wt.%) were prepared by sol–gel method and calcined at 500 °C. These catalysts were employed for the liquid phase condensation of anisole with paraformaldehyde. All the catalysts were characterized by N₂ sorption, XRD, and NH₃-TPD. The activities of synthesized MoO₃/SiO₂ catalysts were compared with p-toluene sulfonic acid (p-TSA), the most frequently used catalyst for the condensation reactions, and with a supported metal oxide (WO _x /ZrO₂). Under the similar reaction conditions, synthesized 10 wt.% MoO₃/SiO₂ catalyst calcined at 500 °C was found to be the most active in the condensation of anisole with paraformaldehyde.     

Dehydration of Glucose to 5-Hydroxymethylfurfural Using Combined Catalysts in Ionic Liquid by Microwave Heating

The dehydration of glucose into 5-hydroxymethylfurfural (HMF) was catalyzed by NKC-9 (a macroporous sulfonated polystyrene ion-exchange resin) combined with metal oxides (TiO₂, ZrO₂, Al₂O₃ calcined at different temperatures). In the combined catalytic system, Al₂O₃ calcined at 550°C exhibited excellent catalytic activity, when the dosage of NKC-9 was kept constant. Four parameters (catalyst dosage, reaction temperature, reaction time, and initial glucose amount) were optimized by employing response surface methodology (RSM), with HMF yield as the response parameter. The maximum HMF yield of 62.09% was obtained at catalyst 0.07 g, temperature 140°C, time 20 min, and glucose 0.01 g. The catalytic activity of the binary catalyst (NKC-9 and Al₂O₃) for the conversion of glucose into HMF did not show significant decrease after five-times uses at 140°C for 20 min.     

Adhesion optimization for catalyst coating on silicon-based reformer

CMZ (ca. 30.0 wt.% Cu, 20 wt.% Mn, and 50 wt.% Zn) catalyst was chosen for the partial oxidation of methanol (POM) reaction. To enhance adhesion between a silicon-based reactor and catalysts, boehmite and bentonite were used as binders. Changes in conditions such as pH value, ratio of bentonite/boehmite, amount of solid contents per area of substrate, and aging time have crucial effects on adhesion and result in variable performance of catalyst in POM reaction. Regarding optimized adhesion conditions, 13 wt.% weight loss was observed and methanol conversion could be kept at ca. 80–90% of original catalyst performance in a packed-bed reactor. However, poor performance was observed in the micro-channel reactor. The methanol conversion (C_MeOH), H₂ selectivity (S_H2), and H₂ yield (Y_H2) achieved 58%, 67%, 5.7 × 10^?6 mol/min in micro-channel reformer at 250 °C, respectively.     

Changes in the chemical composition of V2O5-loaded CVC-TiO2 materials with calcination temperatures for NH3-SCR of NOx

In this study, the aim was to evaluate the effect of calcinations temperature on the catalytic activity and chemical composition of V₂O₅/TiO₂. We prepared V₂O₅-loaded CVC-TiO₂ catalysts by a combination of chemical vapor condensation (CVC) and impregnation method at different calcination temperatures. These catalysts were analyzed for their ability to catalyze NH₃-based selective catalytic reduction of NO_x. Compared with V₂O₅ loaded P25-TiO₂ (commercial). V₂O₅/CVC-TiO₂ catalysts calcined above 200 °C exhibited better performance towards NO_x conversion than that by a commercial catalyst prepared using P25-TiO₂ (calcined at 500 °C). In addition, the NO_x conversion rate obtained with the sample calcined at 500 °C gave the best result (90 %) at a reaction temperature of 200 °C. From the XPS results, we observed that the V^4+/5+ ratio was well balanced when the V₂O₅ loaded CVC-TiO₂ sample was calcined at 500 ºC.     

Al2O3-supported alkali and alkali earth metal oxides for transesterification of palm kernel oil and coconut oil

Transesterification of palm kernel oil (PKO) and coconut oil (CCO) with methanol was investigated under a heterogeneous catalysis system. Various Al₂O₃-supported alkali and alkali earth metal oxides prepared via an impregnation method were applied as solid catalysts. The supported alkali metal catalysts, LiNO₃/Al₂O₃, NaNO₃/Al₂O₃ and KNO₃/Al₂O₃, with active metal oxides formed at calcination temperatures of 450–550 °C, showed very high methyl ester (ME) content (>93%). XRF analysis suggests this is likely to be due to a homogeneous catalysis of dissoluted alkali oxides. On the other hand, Ca(NO₃)₂/Al₂O₃ calcined at 450 °C yielded the ME content as high as 94% with only a small loss of active oxides from the catalyst, whereas calcined Mg(NO₃)₂/Al₂O₃ catalyst possessed an inactive magnesium-aluminate phase, resulting in very low ME formation. At calcination temperatures of >650 °C, alkali metal- and alkali earth metal-aluminate compounds were formed. Whilst the water-soluble alkali metal aluminates formed over NaNO₃/Al₂O₃ and KNO₃/Al₂O₃ were catalytically active, the aluminate compounds on LiNO₃/Al₂O₃ and Ca(NO₃)₂/Al₂O₃ are less soluble, giving very low ME content. The suitable conditions for heterogeneously catalyzed transesterification of PKO and CCO over Ca(NO₃)₂/Al₂O₃ are the methanol/oil molar ratio of 65, temperature of 60 °C and reaction time of 3 h, with 10 and 15–20% (w/w) catalyst to oil ratio for PKO and CCO, respectively. Some important physical and fuel properties of the resultant biodiesel products meet the standards of diesel fuel and biodiesel issued by Department of Energy Business, Ministry of Energy, Thailand.     

On the Efficacy of Ru/Al2O3 Catalyst for Steam Reforming of Ethylene Glycol

This work describes hydrogen (H₂) production via steam reforming of ethylene glycol (EG) over a supported ruthenium catalyst. EG is chosen as a model compound for the alcohols contained in the aqueous phase of bio-oil. Using a fixed-bed reactor, experimental runs are carried out over Ru/Al₂O₃ at various temperatures (350–500°C), ratios of the mass of the catalyst (W) to the molar flow rate (F_O) of EG at the inlet (W/F_O = 0.37 ? 2.38 g h/mol), and feed concentrations (22.3–53.4 wt.% EG in water). The role of Ru in conversion of EG, production of H₂, and product distribution of the carbonaceous species is studied. Reaction pathways previously described in the literature are used to elucidate our results.     

Transesterification of Soybean Oil Over Me/Al2O3 (Me = Na, Ba, Ca, and K) Catalysts and Monolith K/Al2O3-Cordierite

Four different Me/Al₂O₃ (Me = Na, Ba, Ca, and K) powder catalysts prepared by incipient-wetness impregnation, and a K/Al₂O₃-cordierite monolithic catalyst produced by the dipcoating technique were used for biodiesel production. The samples were characterized and studied in the transesterification of soybean oil with methanol at 120 °C and 500 rpm, with a alcohol/oil molar ratio = 32, and a catalyst load = 1 wt% for the powder catalyst and 0.5 wt% for the monolith. The Ca/Al₂O₃, Na/Al₂O₃ and K/Al₂O₃ powder catalysts reported a FAME (fatty acid methyl esters) formation of 94.7, 97.1, and 98.9% respectively after 6 h of reaction. On the other hand, Ba/Al₂O₃ showed little activity (7.6%). The leaching of the alkali and alkaline earth metal species during reaction was important, what indicates that the activity could be explained in terms of a homogeneous–heterogeneous catalyst effect. When the monolithic sample and the powder catalyst were compared (under identical reaction conditions), the production of FAME for the latter was 89.5–59.1% for the monolithic catalyst. After two consecutive runs, the monolithic catalyst presented a partial deactivation of 8% in the FAME yield. The present work shows that the use of monolithic catalysts in the transesterification of vegetable oils is a viable alternative.     

Biodiesel Preparation from Soybean Oil by Using a Heterogeneous Ca<Subscript>x</Subscript>Mg<Subscript>2−x</Subscript>O<Subscript>2</Subscript> Catalyst

Abstract  

An effective heterogeneous catalyst, Ca_xMg_2−xO₂, was prepared and tested for soybean oil transesterification with methanol. The catalysts were characterized by using X-ray diffraction , Fourier transform infrared spectra, thermo gravimetric and differential thermal analysis , and Hammett indicator method. The catalyst with Ca/Mg ratio of 1.0 and calcined at 800 °C exhibited high catalytic activities. Under the suitable transesterification conditions (methanol/oil ratio 12:1, catalyst loading 6 wt%, reaction time 5 h, at reflux of methanol), the oil conversion of 91.3% could be achieved. The catalyst can be easily recovered and reused without significant deactivation.     

Supercritical water gasification of aqueous fraction of pyrolysis oil in the presence of a Ni‐Ru catalyst

This study demonstrated that aqueous fraction of pyrolysis oil can be efficiently gasified into fuel gases methane and hydrogen via supercritical water gasification (SCWG) at moderate temperatures (500–700°C) over Ni_20%Ru_2%/γ‐Al₂O₃ catalyst. All experiments were performed in a bench‐scale continuous down‐flow tubular reactor packed with the catalyst. Carbon gasification efficiency of 0.91 mol/mol‐C (converted into CH₄ and CO₂) was achieved in SCWG of the aqueous fraction of pyrolysis oil (containing 2.98 wt % C) at 700°C in the presence of the catalyst. A similar carbon gasification efficiency (approx. 0.89 mol/mol‐C) was obtained at a lower temperature (600°C) with a diluted feedstock (0.7 wt %C). Scanning Electron Microscopy coupled with Energy Dispersive x‐ray and inductively coupled plasma analysis results confirmed that this catalyst was stable during SCWG of aqueous fraction of pyrolysis oil after 6 h on‐stream. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2786–2793, 2016     

Effects of KF Loading on Mg–Al Mixed Oxides for the Selective Synthesis of Trimethylolpropane Triesters

A series of Mg–Al hydrotalcites (HTCs) calcined at different temperatures were evaluated for their suitability as solid base catalysts for the selective synthesis of trimethylolpropane triesters (TMPTEs) via transesterification of trimethylolpropane (TMP) with a mixture of C₈–C₁₀ fatty acid methyl esters (FAMEs). The effect of potassium fluoride (KF) loading of the calcined HTCs on the physicochemical and catalytic properties of the materials attained was ascertained. Using a 5?wt% catalyst loading and a FAME:TMP molar ratio of 3.5:1 at 170°C for 8?h, the Mg–Al mixed oxide obtained by calcining HTC at 500°C (HTC-500) gave the highest TMPTE selectivity and FAME conversion. Impregnating HTC-500 with 10?wt% KF (KF/HTC-500) generated strongly basic KMgF₃, KOH, K₂O, and coordinatively unsaturated F^? sites. The FAME conversion and TMPTE yield obtained over different HTC and KF/HTC-500 catalysts depended on their total basicity, where a basic strength of 15?H_{_}?3, a common homogeneous base for the polyol ester production.     

On the Production of Hydrogen from Bio-Oil: A Representative Study Using Propylene Glycol

In a bio-refinery focused on fast pyrolysis, hydrogen (H₂) producible from reforming of the aqueous fraction of bio-oil with steam can be utilized for upgrading pyrolytic lignin into fuels by hydrotreatment. In this work, propylene glycol (PG) was chosen as a typical compound symbolizing higher polyols in the bio-oil aqueous fraction. Catalytic processing of PG into H₂ at low temperature (T = 500°C) was investigated using several commercial catalysts such as Ni/Al₂O₃, Ru/Al₂O₃, Ru/C, Pt/C, and Pd/C in a laboratory-scale fixed-bed reactor. The efficiencies of the catalysts were presented as selectivity to CO, CO₂, CH₄ and H₂, and PG conversion into gaseous phase. Wide ranges of temperature (300–500°C), W/F_O (18.6–92.9 g h/mol), and S/C ratio (5.6–12.7 mol/mol) were examined using Ni/Al₂O₃. At T = 500°C, H₂ selectivity (73.7%) and PG conversion (66.2%) were maximized using ratios of catalyst mass to molar flow rate of PG (W/F_O) = 18.6 g h/mol and steam to carbon (S/C) = 12.7 (10 wt% PG solution). It was found that Ni/Al₂O₃ demonstrates stable operation for at least 6 h of time-on-stream. Finally, a plausible reaction pathway for PG reforming was proposed.     

Catalytic Removal of Toluene over Co3O4–CeO2 Mixed Oxide Catalysts: Comparison with Pt/Al2O3

The catalytic oxidation of toluene, chosen as VOC probe molecule, was investigated over Co₃O₄, CeO₂ and over Co₃O₄–CeO₂ mixed oxides and compared with the catalytic behavior of a conventional Pt(1 wt%)/Al₂O₃ catalyst. Complete toluene oxidation to carbon dioxide and water was achieved over all the investigated systems at temperatures below 500 °C. The most efficient catalyst, Co₃O₄(30 wt%)–CeO₂(70 wt%), showed full toluene conversion at 275 °C, comparing favorably with Pt/Al₂O₃ (100% toluene conversion at 225 °C).     

Biodiesel Production from Soybean Oil Catalyzed by Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>

In the present study, we synthesized biodiesel from soybean oil through a transesterification reaction catalyzed by lithium carbonate. Under the optimal reaction conditions of methanol/oil molar ratio 32:1, 12 % (wt/wt oil) catalyst amount, and a reaction temperature of 65 °C for 2 h, there was a 97.2 % conversion to biodiesel from soybean oil. The present study also evaluated the effects of methanol/oil ratio, catalyst amount, and reaction time on conversion. The catalytic activity of solid base catalysts was insensitive to exposure to air prior to use in the transesterification reaction. Results from ICP-OES exhibited non-significant leaching of the Li₂CO₃ active species into the reaction medium, and reusability of the catalyst was tested successfully in ten subsequent cycles. Free fatty acid in the feedstock for biodiesel production should not be higher than 0.12 % to afford a product that passes the EN biodiesel standard. Product quality, ester content, free glycerol, total glycerol, density, flash point, sulfur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value fulfilled ASTM and EN standards. Commercially available Li₂CO₃ is suitable for direct use in biodiesel production without further drying or thermal pretreatment, avoiding the usual solid catalyst need for activation at high temperature.     

Catalytic Synthesis of Thiophene from the Reaction of Furan and Hydrogen Sulfide

The catalysts were prepared from pseudo-boehmite mixed with dilute nitric acid and calcined at different temperatures. The vapour-phase reaction of furan and hydrogen sulfide was performed in a fixed-bed flow in the presence of catalyst. The catalysts were characterized by XRD, N₂ adsorption, FT-IR techniques. The Al₂O₃ calcined at 550 °C has large surface areas which resulted in high yield of thiophene under the conditions: at atmosphere, reaction temperature 500 °C, the ratio of H₂S to Furan about 10 (mol) and LHSV 0.2 h⁻¹. The reaction mechanism was proposed for the synthesis of thiophene from furan and hydrogen sulfide over Al₂O₃.     

Feasibility of Palm Oil as the Feedstock for Biodiesel Production via Heterogeneous Transesterification

The production of biodiesel has become popular recently as a result of increasing demand for a clean, safe and renewable energy. Biodiesel is made from natural renewable sources such as vegetable oils and animal fats. The conventional method of producing biodiesel is by reacting vegetable oil with alcohol in the presence of a homogenous catalyst (NaOH). However, this conventional method has some limitations such as the formation of soap, usage of significant quantities of wash water and complicated separation processes. Heterogeneous processes using solid catalysts have significant advantages over homogenous methods. Currently, more than 90 % of world biodiesel is produced using rapeseed oil. The production of biodiesel from rapeseed oil is considered uneconomical, considering the fact that palm oil is currently the world's cheapest vegetable oil. Therefore, the focus of this study is to show the feasibility of producing biodiesel from palm oil using montmorillonite KSF as a heterogeneous catalyst. The heterogeneous transesterification process was studied using design of experiment (DOE), specifically response surface methodology (RSM) based on a four‐variable central composite design (CCD) with α = 2. The transesterification process variables were reaction temperature, x₁ (50–190 °C), reaction period, x₂ (60–300 min), methanol/oil ratio, x₃ (4–12 mol mol^–1) and the amount of catalyst, x₄ (1–5 wt %). It was found that the conversion of palm oil to biodiesel can reach up to 78.7 % using the following reaction conditions: reaction temperature of 155 °C, reaction period of 120 min, ratio of methanol/oil at 10:1 mol mol^–1 and amount of catalyst at 4 wt %. From this study, it was shown that montmorillonite KSF catalyst can be used as a solid catalyst for biodiesel production from palm oil.     

Stabilization of bio-oil over a low cost dolomite catalyst

A low cost alkaline catalyst of dolomite (CaMg(CO₃)₂) was used to stabilize acacia sawdust bio-oil mixed with methanol. The upgrading efficiency was evaluated in terms of the total acid number (TAN) and viscosity. A change in the dolomite calcination temperature from 700 to 900 °C led to a significant change in the TAN and viscosity of the methanol-added bio-oil. Dolomite activated at higher temperatures had larger amounts of active CaO and MgO species due to the enhanced decarboxylation of calcium and magnesium carbonates. An increase in the dolomite content (1-5 wt%) decreased the TAN value of bio-oil remarkably. A thermal aging test of the methanol-added bio-oil upgraded using dolomite (calcined at 900 °C) at 50 °C for 24 h was carried out by storing the bio-oil at 80 °C for one week. Although the TAN value increased after the aging process, it was still lower than the TAN of raw bio-oil. In addition, increasing the methanol content (10-30 wt%) decreased the TAN and viscosity of the bio-oil significantly.     

Transesterification of Rapeseed Oil for Synthesizing Biodiesel by K/KOH/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> as Heterogeneous Base Catalyst

The heterogeneous base catalyst, γ-Al₂O₃ loaded with KOH and K (K/KOH/γ-Al₂O₃) was first prepared and used in the transesterification of rapeseed oil with methanol to produce biodiesel. The prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller method, infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that when γ-Al₂O₃ is loaded with KOH and K, the Al–O–K species is produced, resulting in an increase in the catalytic activity. The impacts of catalyst preparation conditions on the catalytic activities of K/KOH/γ-Al₂O₃ were investigated. The results demonstrate that the catalyst K/KOH/γ-Al₂O₃ has high catalytic activity when the added amounts of KOH and K are 20 and 7.5 wt% respectively. The transesterification of rapeseed oil to biodiesel with the prepared heterogeneous base catalyst was optimized. It was found that the yield of biodiesel can reach as high as 84.52% after 1 h reaction at 60°C, with a 9:1 molar ratio of methanol to oil, a catalyst amount of 4 wt%, and a stirring rate of 270 g.