Iranian Journal of Chemical Engineering (IJChE)

Abstract The SrO-CaO-Al₂O₃ nanocatalysts were prepared and optimized using the co-precipitation method. In this work parameters affecting the catalytic performance for the production of biodiesel from sunflower oil have been investigated. Thev response surface methodology (RSM) has been used to assess the impact of operational conditions on the production of biodiesel, with the biodiesel yield as the response variable. The catalyst was found to be calcined at 600 °C, with a 5-hour calcination time, 75 minutes of the aging time, and a precipitation temperature of 50 °C as optimal conditions for the production of biodiesel. The results showed that the optimal reaction conditions were CH₃OH/oil=12/1 at 60 ˚C with the concentration of 6wt.%of the catalyst and reaction time of 3 h at stirring speed of 600 rpm. Furthermore, the biodiesel yield reached 99% under optimal operational conditions. The SrO-CaO-Al₂O₃ nanocatalysts were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms-infrared spectroscopy (FT-IR), and N₂adsorption–desorption measurements methods. The kinetic study has been done and the first order kinetic model was found  in agreement with experimental results (R²= 0.998). From the kinetic studies, E_a=41.57 kJ.mol^–1 and A= 5.25×10⁵ L.mol^-1s^-1 were obtained.

Abstract In the present work, the effect of synthesis method (simultaneous impregnation and coprecipitation) and copper to nickel active phases loading were investigated in Ni-Cu-Al catalysts. The water/ethanol molar ratio of 6 and gas hourly space velocity (GHSV) of 20000 hr^-1 were used in all the experiments. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) techniques. The catalytic activity results revealed that 13Ni-6Cu/γ-Al₂O₃ impregnated catalyst was more active than co-precipitated one (13NiO-6CuO-81Al₂O₃) in the same amount of compositions of active metals and Al₂O₃, but by increasing the active phases (Cu and Ni) loading in co-precipitated catalysts (24NiO-31CuO-45Al₂O₃, 31NiO-24CuO-45Al₂O₃, 40NiO-15CuO-45 Al₂O₃ and 47NiO-8CuO-45Al₂O₃), they achieved a better performance than 13NiO-6CuO-81Al₂O₃ catalyst. The 40NiO-15CuO-45Al₂O₃ catalyst showed 99% ethanol conversion, as well as 303 hydrogen yield and 4% CO selectivity at 470^oC. SEM images revealed agglomerated particles for the samples with high Al₂O₃ content and with increasing the active phase content in the catalyst the particle sizes decreased. The 40NiO-15CuO-45Al₂O₃ showed smallest particle size among the catalysts.

Abstract In the presented research, the selective hydrogenation of benzene in a mixture of benzene and normal heptane (5 vol % of benzene) over different kinds of heterogeneous catalysts was investigated. For this purpose, a series of catalysts with various supports such as Pd/ZSM-5, Pd/13X and Pd/  was developed. To prepare Pd supported catalysts, the modification of supports was conducted by a specified amount of palladium nitrate in the aqueous solution. Experimental catalyst evaluation tests were performed in the catalyst assessment set-up. The characterizations of the physicochemical properties of the prepared catalysts were performed by XRD, NH₃-TPD and BET. It can be found that the conversion of benzene was promoted under the optimized reaction conditions of 200 °C, 1 MPa, H₂/HC = 1.3 (molar ratio) and the weight hourly space velocity (WHSV) = 25 hr^-1. Among these catalysts, Pd/13X exhibited the maximum conversion of benzene (90 %) and the minimum light-cut production under the optimum conditions. The study on the stability of catalysts shows that, the decline activity of Pd/13X catalyst is more than that of the other catalysts (from 90 % to 81 %) in the specified 20 h time on stream, but so far the activity of this catalyst is the highest in comparison with that of other catalysts at the end of the defined time (20 h).

Abstract The Micromixing plays a key role in the most of industrial processes; enhancing its efficiency is a very important issue. In this study, a typical rotating packed bed (RPB) reactor equipped with the blade packing and high frequency ultrasonic transducers were designed to study the micromixing efficiency using the iodide/iodate reaction. The utilized ultrasonic transducers were ultrasonic atomizer humidifiers with the frequency of 1.7 MHz. Taking advantage of both the controllable high gravitational force and induced effects of the high frequency ultrasound, simultaneously, in a small volume reactor is the novelty of the present work. The effects of different parameters like the rotational speed, volumetric ratio, concentration of acid, ultrasonic power and number of activ transducers were investigated with and without the ultrasonic field. By increasing the rotational speed and volumetric flow, the segregation index decreased and by increasing the concentration of acid and volumetric ratio, the segregation index increased. In all of experiments, the segregation index decreased significantly under the ultrasonic field. Moreover, by increasing the ultrasonic power and number of active transducers the segregation index decreased. The obtained results indicated that the relative segregation index increased up to 41.1 % under the 1.7 MHz ultrasonic field. Therefore, the high frequency ultrasonic waves can intensify micromixing, even in a high efficiency equipment like RPB

Abstract In this work, the effect of the Si/Al ratio on the activity of zeolite supported bimetallic (Ni-Co) catalysts for Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel methods and then calcined at 550 °C for 2 h. The catalysts were characterized by XRD, XRF, FESEM, BET and TGA. All samples were tested in a micro reactor at three different temperatures (i.e. 700, 750, and 800 °C). Micro reactor test results showed that 800 °C was the proper temperature for DRM. The catalyst with 5 wt % of Ni and 2.5 wt % of Co supported on γ-Alumina have shown a higher H₂/CO ratio than other samples. For the zeolite supported catalysts when Ni/Co=2/1, the surface area and pore volume decreased but the H₂/CO ratio increased by increasing the Si/Al ratio. Reverse the Water Gas Shift (WGS) reaction was not very active when the catalyst and support showed a basic property. Also, the stability of the catalysts has been tested for 30h on stream.

Abstract The impregnation of the alumina support with the PdCl₂ solution was investigated in batch and semi-batch operation modes using a recycle packed-bed reactor. The UV-visible analysis was used to evaluate the kinetics of the adsorption of Pd on the alumina support. The adsorption data related to transient palladium showed that the adsorption of Pd was very rapid and completed within few minutes. Bi-metallic Pd-Ag/Al₂O₃ catalysts were synthesized by the sequential impregnation method. CO-chemisorption, CO-TPD and FE-SEM tests were used to characterize the synthesized bi-metallic samples. The catalytic performance of the samples was evaluated for the tail-end acetylene selective hydrogenation process in a fixed-bed reactor. Moreover, the deactivation of the catalysts was evaluated mathematically by the integral method of analysis, considering reaction kinetics as power laws in terms of n^th orders in H₂ and C₂H₂ partial pressures. It was observed that by the batch-wise addition of the Pd precursor solution, a sample, with the lowest amount of Pd dimmers that had the highest ethylene selectivity and lowest hydrogenation reaction rate, was obtained.

Abstract The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates, that is, 5, 10 and 15 °C/min were applied after incipient wetness impregnation of the support (1.6–1.8 mm in diameter) with KNO3. The obtained catalysts were characterized by N2 physisorption, SEM-EDAX analysis and XRF for textural and chemical properties. Catalytic performance tests were performed in a fixed-bed quartz reactor under kinetically controlled conditions for proper catalyst screening. The EDAX measurement results illustrated that the potassium concentration profile changed with drying rate with the catalyst prepared by lower drying rate exhibited highest K concentration at the center as well as highest propylene yield. These were attributed to the retraction of impregnation solution during drying at slow rates which results in lower concentration of acidic sites in catalyst center, thereby reducing the contact time of the propylene product with strong acid sites during reaction.

Abstract One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation method. X-ray diffraction (XRD) analysis showed that crystalline sizes of Ce0.9Cu0.1O1.9 and 5Cu/Cu0.1Ce0,9O1.9 were 9.22 and 18.33 nm, respectively. The Catalysts were evaluated in medium temperature shift reaction at 300-390 °C and at gas hourly space velocities (GHSV) of 12000 and 30000 h-1, in a fixed bed reactor. Due to higher concentration of Cu and synergic positive effects of both active metal and support, 5Cu/Cu0.1Ce0,9O1.9 catalyst showed better performance. It was also concluded that, because of low residence time at high levels of GHSV, increasing GHSV leads to decrease CO conversion. Then 5Cu/Cu0.1Ce0,9O1.9 was evaluated in microchennel reactor in 2 GHSVs of 12000 and 30000 h-1 and results were compared with the fixed-bed reactor. It can be concluded that microchannel reactor is better in higher GHSVs (lower residence time of gas flow). A microchannel reactor provides a high surface-to-volume ratio and gases pass over the thin layer of catalyst on the coated plates. Hence, due to the better access to the catalytic bed, the reactants react even in a short time, which improves the microchannel performance compared to the fixed bed reactor

Abstract In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar and the registration of adsorption capacity with passing of time. Experimental data were adjusted with adsorption isotherm models including two and three parameters isotherm. Also the process was studied in terms of kinetic models and after the implementation of the experimental data with kinetic models, the speed of this process equations were obtained. The best kinetic model for this process was selected first order equation. The results showed that adsorption capacity of 13X is 71.5 mg/g at pressure of 8 bars. Also the result indicate that 13x has high capacity at low pressures. With regard to achieved results for adsorption isotherm modeling, the adsorption isotherm followed of the three-parameter and among three-parameter models, Toth isotherm can be interpreted the process. Also the results of the fixed bed indicate a very high adsorbent selectivity to carbon dioxide adsorption and there was little oxygen and nitrogen adsorption.

Abstract Pharmaceutical pollutants are one of the most important issues of modern life and their negative effects on the environment and human health are undeniable. In the present work, the effectiveness of the photocatalytic process was studied by two semiconductors (ZnO and V2O5) in order to remove the Diclofenac Sodium completely under solar irradiation. The study examined the impact of parameters such as the high-level range concentration of pharmaceutical, catalyst dosage, pH changes and time on the photodegradation of Diclofenac Sodium in aqueous solution. All the experiments were carried out under solar and UV irradiation to compare between the two circumstances. The optimum conditions obtained for photodegradation of Diclofenac Sodium were: reaction time 180 min, zinc oxide and vanadium pentoxide = 1 g L-1, Diclofenac Sodium concentration = 300 mg L-1 and pH = 4. In addition, chemical oxygen demand removal was investigated for all the conditions and total degradation was observed by V2O5 under optimum conditions. The study of reaction kinetics was carried out at optimum conditions and approximately a pseudo-first order kinetic model was in agreement with experimental results in each case.

Abstract DEB dehydrogenation reaction was conducted to produce divinylbenzene (DVB) and ethylvinylbenzene (EVB). The effects of temperature, catalyst weight and time factor on the performance of the dehydrogenation reactor were investigated experimentally. Temperature was varied from 550º C up to 600 º C. Temperature affect the conversion of DEB to DVB significantly. The mole fraction of DEB in the outlet of the reactor is reducing up to 580 º C, but further increase in temperature up to 600 º C does not decrease the mole fraction of DEB in the outlet of the reactor. Catalyst weight was varied from 10 gr up to 40 gr. The results showed that the trends of EVB+DVB production and DEB consumption are identical at various catalyst weights. To obtain optimum time factor for the DEB dehydrogenation process experiments were conducted at various time factors. The results showed that the optimum time factor for DVB as a desired product is 825 gr/hr.mole. . The data and information provided in this research can be used for scale-up and optimization purposes.

Abstract The nitrogen doped TiO2 as heterogeneous photocatalyst via sol-gel method were successfully synthesized. The physicochemical, morphological and textural characteristics of the obtained TiO2 samples were characterized by advanced analysis techniques. The photocatalytic activity of the samples were evaluated for degradation of 4-CP under solar irradiation. The as-synthesized photocatalysts were characterized with X-ray diffraction (XRD), surface area measurements (BET and BJH), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS) and energy dispersive X-ray spectrum (EDX). The activities of as-prepared TiO2 photocatalysts were examined for the degradation of 4-Chlorophenol aqueous solution under solar irradiation in a photoreactor and photocatalytic degradation mechanism and pathway have been investigated. The results show that the 3% wt. N-doped TiO2 nanoparticles under conditions (solution pH of 4.0, catalyst loading of 2 g/L, initial 4-CP concentration of 10 mg/L, Time of 8 h) exhibits much higher photocatalytic degradation efficiency (91%) as compared with that of 5% wt. N-doped (83%), 1% wt. N-doped (71%), and pure TiO2 (35%).

Abstract The catalytic reduction of sulfur dioxide with methane to form elemental sulfur has been studied.
Al2O3, Cu-Al2O3 and Ni-Al2O3 were examined as catalysts and their performances were compared in terms of SO2 conversion and selectivity. Performance of the catalyst extremely enhanced when nickel and copper were added as promoters. The effects of temperature, SO2/CH4 molar ratio, and reaction time on SO2 reduction were studied. The operating temperature range was 550–800 °C and it was observed that the reaction is strongly temperature dependent.
At temperatures lower than 700 °C, Al2O3-Cu (10%) catalyst showed the best performance of all the catalysts. But, at 700° and higher, performances of Al2O3-Cu (10%) and Al2O3-Ni(10%) catalysts were similar. Complete conversion and selectivity (more than 99.5%) was achieved by Al2O3-Cu (10%) and Al2O3-Ni(10%) catalyst, at 750 °C. Effect of molar feed ratio of SO2/CH4= 1-3 was studied and stoichiometric feed ratio showed the best performance. Also, investigation of reaction time for Al2O3-Cu(10%) and Al2O3-Ni(10%) catalysts showed a good long-term stability for SO2 reduction with methane.

Abstract The high silica Mn-substituted MFI metallosilicate catalyst with Si/Al molar ratio of 220 and Si/Mn molar ratio of 50 was successfully synthesized by hydrothermal method. The catalyst sample was appropriately characterized by XRD, FE-SEM, EDX and BET techniques. The Mn-substituted MFI metallosilicate has not been reported as the potential catalyst for the methanol to propylene (MTP) reaction. The prepared catalyst was examined in the MTP reaction at the optimal operating conditions. Furthermore, for elucidating the flow field of the MTP fixed bed reactor, a three-dimensional (3D) reactor model was developed. A detailed reaction mechanism which was proposed for the MTP reaction over the Mn-impregnated MFI zeolite (Mn/H-ZSM-5) was properly employed. The reaction mechanism was integrated to a computational fluid dynamics (CFD) for simulating the kinetic, the energy equation and the hydrodynamics of the MTP process, simultaneously. The component distribution during proceeding of the MTP reaction was also simulated as a function of time on stream. The CFD modeling results were validated by the actual data which were obtained over the Mn-substituted MFI metallosilicate catalyst. With regard to the findings, the experimental data were in good agreement with the predicted values of the CFD modeling.

Abstract Furfural is one of the most promising chemical platforms with bright perspective with respect to the production of biobased chemicals and fuels from lignocellulosic material. Globally, the majority of this biomass derived chemical is converted into furfuryl alcohol, a building block in polymers industry. The vapor-phase hydrogenation of furfural over copper species dispersed on two types of silica (bulk-type and nano-sized) supports with or without chromium as a promoter was studied for the first time. The catalysts were synthesized via impregnation method and operated under mild hydrogenation reaction conditions. The results represented that the catalytic performance of the nano-sized silica-supported catalyst was better in terms of furfural conversion, furfuryl alcohol yield and selectivity than that of the bulk-type silica after 4 hours of operation. However, by incorporation of chromium as a promoter, the bulk-type silica-supported catalyst exhibited an improved performance during the whole run length (higher than 82% and 96% of furfural conversion and furfuryl alcohol selectivity, respectively).

Abstract Catalytic naphtha reforming is one of the most important processes in which, low quality naphtha is converted into high octane motor gasoline. In this study, a mathematical model was developed and was used for investigation the effect of temperature, pressure, hydrogen to hydrocarbon ratio on the octane number, the yield of product and the undesirable phenomena of coke deposition in a semiregenerative catalytic reforming unit. The result of the model was compared to the plant data to verify the model accuracy. Then, the model was used to find the optimal condition for the maximum value of octane number and yield of product and the minimum value of coke deposition. The optimum condition of the process is estimated using genetic algorithm optimization method as an efficient optimization method. In the optimal condition, the octane number and the yield of the product are improved 0.3% and 1.23% respectively, and the coke deposition is reduced 2.1 %.

Abstract In this paper, catalytic oxidation of CO over the LaFe1-xCuxO3 (x= 0, 0.2, 0.4, 0.6) perovskite-type oxides was investigated. The catalysts were synthesized by sol-gel method and characterized by XRD, BET, FT-IR, H2-TPR and SEM methods. The catalytic activity of catalysts was tested in catalytic oxidation of CO. XRD patterns confirmed the synthesized perovskites to be single-phase perovskite-type oxides. The synthesized perovskite catalysts show high activity in the range of reaction temperature (50 - 300 ºC). The substitution of Cu in B-site of the perovskite catalysts enhanced their catalytic activity for CO oxidation. Among different synthesized perovskite catalysts, LaFe0.6Cu0.4O3 has the highest activity: nearly complete elimination of CO was achieved at 275 ºC with this catalyst. Kinetic studies for CO oxidation were performed based on power law and Mars-van Krevelen mechanisms. According to kinetic calculations, the most probable mechanism is the MKV-D (dissociative adsorption of oxygen) which can predict the experimental data with correlation coefficient of R2 > 0.995.

Abstract Abstract
Gas to liquid (GTL) process involves heterogeneous catalytic chemical reactions that convert synthesis gas to hydrocarbons and water vapor. A three phase reactor, called Low temperature Fischer-Tropsch (LTFT) is commonly applied for GTL process. In this reactor the gaseous phase includes the synthesis gas, light hydrocarbons and water vapor, the liquid phase is a mixture of the heavy hydrocarbons, and the solid phase is composed of the catalyst and the waxy products. The presence of the liquid phase in LTFT reactor causes mass transfer restriction, affecting the reaction conversion. In this work a numerical simulation of the LTFT fixed bed reactor in trickle flow regime has been accomplished to understand the impact of the liquid phase on the reactor performance. For this purpose, we have developed an axisymmetric two-dimensional multiphase heterogeneous model, where contain carbon monoxide and hydrogen, are transferred into the liquid phase. The reactor consisted of a shell and a tube that was filled with the spherical cobalt catalyst. The reaction conditions were as follows: the wall temperature was 473 K, pressure was 20 bars and a gas hour space velocity (GHSV) was 111 Nml.g_cat^(-1).h^(-1). The numerical simulation results proved the negative impact of the liquid phase on the reaction conversion. The model predictions were evaluated against the reported experimental data and also compared with the result of a numerical pseudo-homogeneous model. It was found that applying the heterogeneous model instead of the pseudo-homogeneous model clearly decreases the deviation of the numerical results.

Abstract In this research, photocatalytic degradation method has been introduced to clean up Spent Caustic of Olefin units of petrochemical industries (neutralized Spent Caustic by means of sulfuric acid) in the next step, adaptable method and effective parameters in the process performance have been investigated. Chemical oxygen demand (COD) was measured by the commercial zinc oxide that synthesized with precipitation synthesis method in a two-shell photoreactor. The percent of reduction of COD in the photocatalytic process was modeled using Box–Behnken design and artificial neural network techniques. It was concluded that the ANN was a more accurate method than the design of experiment. The effect of important parameters including oxidant dosage, aeration rate, pH, and catalyst loading was investigated. The results showed that all of the parameters, except pH, had positive effects on increasing COD removal. According to the obtained results, adsorption and photolysis phenomena had a negligible effect on COD removal.

Abstract In the present study, Choline hydroxide (ChOH) as an ionic liquid catalyst was used for transesterification of soybean oil into biodiesel in a microchannel reactor. The effects of three variables i.e. reaction temperature, catalyst dosage and total flow rate on fatty acid methyl ester (FAME) content (wt. %) were optimized using Box–Behnken experimental design. In order to predict the FAME content a quadratic polynomial model was obtained. The optimal conditions from the model were reaction temperature of 53.53 °C, catalyst dosage of 2.6 wt. % and total flow rate of 11.82 mL/min. At these conditions, the predicted FAME content was 96.45 wt.% and the experimental FAME content was obtained 97.6 wt. %. The proximity of the experimental results and predicted values showed that the regression model issignificant. Using the ionic liquid catalyst in the studied microreactor for transesterification leads to diminish the reaction time to the order of seconds compared to conventional batch systems. In addition, the reusability of ChOH catalyst was investigated. The results revealed that the catalyst had perfect utility after several runs without much loss in the activity.

Abstract An alumina-supported nickel catalyst was prepared by impregnation of Ni2+ solution onto mesoporous alumina under microwave irradiation (denoted as M-Ni/Al2O3). For comparison, a catalyst with the same nickel content was prepared by conventional impregnation method (denoted as UM-Ni/Al2O3). Both M-Ni/Al2O3 and UM-Ni/Al2O3 catalysts were applied to the syngas (H2 + CO) production by methane oxy-steam reforming in order to investigate the effect of preparation method on the catalytic performance. The reaction experiments were performed in a fixed-bed continuous flow reactor under atmospheric pressure. M-Ni/Al2O3 catalyst exhibited higher methane conversion (XCH4: 0.94) than UM-Ni/Al2O3 (XCH4: 0.58) in the oxy-steam reforming reaction. In addition, the value of syngas yield in M-Ni/Al2O3 (3.21 mole per mole of methane) was almost twice of one for UM-Ni/Al2O3 catalyst (1.59 mole per mole of methane). Various operating conditions such as the influences of the O2/CH4 and H2O/CH4 feed ratios, temperature, and GHSV on the methane conversion and yield of products were investigated. According to the structural characterization (FTIR, XRD, N2 adsorption/desorption, H2-TPR and TEM), the excellent catalytic performance of M-Ni/Al2O3 catalyst was reasonably attributed to the nano size and uniform distributed nickel species (<6 nm) which interacted to the alumina support strongly.

Abstract The present paper deals with the kinetics and mechanism of homogeneously Ir(III) chloride catalyzed oxidation of D-mannitol by chloramine-T [CAT] in perchloric acid medium in the temperature range of 30 to 45 0C. The reaction is carried out in the presence of mercuric acetate as a scavenger for chloride ion. The experimental results show first order kinetics with respect to the oxidant [CAT] and catalyst [Ir(III)] while zero order with respect to substrate, i.e., D-Mannitol was observed. The reaction shows negligible effect of [Hg(OAc)2], [H+] and ionic strength of the medium. Chloride ion positively influence the rate of reaction. The reaction between chloramine-T and D-Mannitol in acid medium shows 2:1 stoichiometry. To calculate activation parameters, the reactions have been studied at four different temperatures between 30 to 45ºC. A mechanism involving the complex formation between catalyst and oxidant has been proposed. Mannonic acid has been identified chromatographically and spectroscopically as the final product of oxidation of D-Mannitol. Based on the kinetic data, reaction stoichiometry and product analysis, a reaction mechanism has been proposed and rate law has been derived.

Abstract Two Cu-Co and Co3O4 oxides were synthesized by the conventional sol-gel auto-combustion and their physical-chemical properties were characterized by XRD, FTIR, SEM, TPR and XPS. The XRD results indicated that copper-cobalt oxide appeared in a mixture form of Cu0.15Co2.85O4 spinel and CuO phases, whereas the cobalt oxide exhibited in the pure form of Co3O4 spinel. The FTIR approved the formation of the spinel structure in the both samples. The SEM results showed that both oxides are as nanoparticles. Application of the same synthesis conditions for both samples let to obtain samples with different purity. The results of temperature program reduction (TPR) revealed that Cu-Co nano oxide is more reducible at lower temperatures. The copper-cobalt oxide exhibited the higher activity that the Co3O4 in catalytic combustion of toluene, which is explained by its higher reducibility at the reaction conditions and by a possible synergistic effect between Cu-Co oxide and CuO particles.

Abstract Methanol steam reforming plays a pivotal role to produce hydrogen for fuel cell systems in a low temperature range. To accomplish higher methanol conversion and lower CO production, the reaction was catalyzed by CuZnFe mixed oxides. Various ratios of Fe and Cu/Zn were coprecipitated in differential method to optimize the CuZnFe structure. The sample containing 45Cu50Zn5Fe (Wt. %) revealed its maximum methanol conversion of 98.4 % and CO selectivity of 0.78 % with operating conditions of gas hourly space velocity of 18000 h-1 and steam to carbon ratio of 1.3 at 270 °C. The synthesized catalysts were analyzed by powder X-ray diffraction, N2 adsorption/desorption, temperature programmed reduction, scanning electron microscopy techniques. The results revealed that the prepared samples presented mesoporous structure with different pore size depending on the Cu/Zn/Fe ratios. The results showed that increase in Fe loading to 20 Wt. % empowered methanol conversion and decreased CO selectivity. Moreover, the optimized catalyst activity was kept constant during 17 h time on stream. Besides, operating conditions of gas hourly space velocity and steam to carbon ratios were evaluated.

Abstract This study presents the synthesis of polyvinyl acetate (PVAc) by solution polymerization and its partial hydrolysis to polyvinyl alcohol (PVA) using alkaline alcoholysis. The influence of the molar ratio of hydrolysis catalyst (NaOH) to PVAc and the time and temperature of the saponification reaction on the degree of hydrolysis and molecular weight of the PVA were investigated using response surface methodology. Statistical analysis of the results revealed that the degree of hydrolysis and molecular weight of PVA were strongly dependent on the molar ratio of NaOH/PVAc. It was also found that the second-order interactions between the investigated parameters were not statistically significant. The optimal conditions for synthesizing PVA as a primary suspending agent were obtained as T = 45°C, t = 33 min and NaOH/PVAc (molar ratio) = 0.05. The chemical structures of the PVAc and the optimum PVA were studied by Fourier transform infrared spectroscopy. The distribution of acetate groups in the optimum PVA was determined using 13C nuclear magnetic resonance spectroscopy. It was found that addition of benzene as well as one-step addition of NaOH (when compared with drop-wise addition) result in more blockiness in the acetate group distribution of PVA. The performance of the optimum PVA was also investigated for a typical suspension polymerization of vinyl chloride and the particle morphology of the product was studied using scanning electron microscopy.