Fixed-bed Microreactor Research Articles

Preparation of Pt/CeL reforming catalyst and its performance in the aromatization of naphtha

To solve the problems of chlorine loss and equipment corrosion caused by the conventional alumina-type reforming catalyst, zeolite L was modified with Ce3+ by ion exchange method and with Ce3+-modified L (CeL) as the support, the Pt/CeL reforming catalyst without any chlorine was prepared by impregnation method. The CeL support and Pt/CeL catalyst were characterized by XRD, N2 adsorption-desorption, NH3-TPD and Py-FTIR; the catalytic performance of Pt/CeL in aromatization was investigated in a continuous-flow fixed-bed micro-reactor, with an industrial hydrofining naphtha containing 0.50 μg/mL sulfur as the feedstock. The results indicate that the modification with Ce3+ by ion exchange has little influence on framework structure of zeolite L; however, it can raise the acid content and acid strength of the CeL support and then remarkably enhance the performance of the Pt/CeL reforming catalyst in aromatization. The activity and selectivity of the Pt/CeL catalyst are comparable to those of the commercial alumina-type reforming catalysts, suggesting that proper acidity can facilitate the aromatization reaction.

Hydrogen production from steam reforming of ethanol over Ni-Co bimetallic catalysts and MCM-41 as support

Abstract Catalytic Steam reforming of ethanol (SRE) is a promising method for the generation of H2 as a clean carrier of energy. In this study, the impregnation method was deployed to prepare mono and bimetallic catalyst Nix-Co(10-x) (x = 10, 9, 8, 5 and 0) loaded on MCM-41 nanoparticles as the catalyst for the SRE reaction. The characteristics of the synthesized catalysis were identified using BET, XRD, EDS, FESM, and TGA/DTA analysis in a fixed bed micro-reactor, the gases were constantly monitored by using gas chromatography (GC). The purpose of this project is to optimize the reaction conditions using synthesized catalysts and to find the best catalyst. The effects of reaction temperature (420–500 °C) and molar ratios of steam to ethanol (S/E = 2, 3 and 5) were studied in detail over this catalyst. According to the results, the performance of bimetallic catalysts is very high compared to mono metal catalyst. Between mono metal catalysts Nickel was active rather than Cobalt. Ni9 Co1/MCM-41 catalysts displayed the best catalytic performance, so that the conversion of ethanol was 90% and highest hydrogen yield of 80% were achieved at the temperature of 490°C, S/E = 5 and under the atmospheric pressure.

Dimerization of Isobutene in C4 Mixtures in the Presence of Ethanol Over Acid Ion-Exchange Resin DH-2

Isobutene dimerization of C4 mixtures with the simulated components of industrial fluid catalytic cracking (FCC) gas stream was carried out in a fixed-bed microreactor over the acid ion-exchange resin (DH-2) in the presence of ethanol. The influences of ethanol/isobutene molar ratio and reaction temperature on the isobutene dimerization reaction were studied. For 1-butene, both isomerization and oligomerization simultaneously take place, but the isomerization reaction is more sensitive to reaction temperature than oligomerization. And both reactions were inhibited noticeably in the presence of ethanol. Although the conversion of isobutene was reduced to some extent when ethanol was introduced, it was beneficial for improving the weight fraction of dimers in oligomers as well as trimethylpentenes in dimers. With ethanol addition, the dimerization reaction was less sensitive to the reaction temperature thus the isobutene dimerization reaction can be performed in a wide temperature range.

Selective hydrogenation of aromatics in coal-derived liquids over novel NiW and NiMo carbide catalysts

Novel bimetallic NiW/Al2O3 and NiMo/Al2O3 carbide catalysts were prepared by temperature-programmed reaction with CH4-H2 mixture. The catalysts were characterized by N2 adsorption, XRD, TPR and their performance for selective hydrogenation of aromatics in coal derived liquids were compared with their sulfide counterparts. Direct coal liquefaction oil (DCLO) fraction in 180∼290 °C and aromatic component separated from low temperature coal tar (LTCT) fraction in 210∼290 °C were selected as feedstock and hydrogenated on a fixed bed micro-reactor. The results of elemental analysis, simulated distillation and GC-MS show that the hydrodearomatization (HDA) activity was: NiMo-C > NiW-C > NiW-S > NiMo-S. The HDA, Hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) for DCLO hydrogenation over NiMo-C is 91%, 29.54% and 75.23%, respectively. The hydroaromatics and cycloalkanes in hydrogenated LTCT and DCLO products were 67.1% and 74.8%, respectively. Thus, NiMo carbide is a promising catalyst for selective hydrogenation of CDLs to obtain high performance jet fuel blend which is rich in hydroaromatics and cycloalkanes.

Production of aryl oxygen-containing compounds from catalytic pyrolysis of bagasse lignin over LaTi Fe1−O3

Abstract A new approach, named production of aryl oxygen-containing compounds from the catalytic pyrolysis of bagasse lignin (BL) over perovskite oxide, was proposed. A series of LaTixFe1−xO3 (LTF-x) samples were prepared by the solid state reaction method. The crystal phase and morphology of LTF-x were characterized by XRD and SEM respectively. Catalytic pyrolysis performance of LTF-x was performed by TG-DTG and the distribution patterns of gaseous, liquid and solid products from BL was investigated using a fixed-bed micro-reactor. The optimal reaction conditions were determined: the pyrolysis temperature was 600 °C, the mass ratio of mBL:mLTF-0.2 was 3:1, the velocity of carrier gas was 100 ml·min−1. The gaseous products were mainly composed of CO2, CO, CH4 and CnHm (n = 2–4, m = 2n + 2 or m = 2n). The main aryl oxygen-containing compounds in liquid products were phenolics, guaiacols, syringols and phenylates, the rest were benzenes, furans, esters and carboxylic acid. The total contents of aryl oxygen-containing compounds were from 62% up to more than 72% under the action of the perovskite. Moreover, the LTF-0.2 sample had nice regenerability.

Green and rapid synthesis of iron molybdate catalyst by mechanochemistry and their catalytic performance for the oxidation of methanol to formaldehyde

Iron molybdenum catalyst was successfully prepared by mechanochemistry method under ball grinding mill. The physico-chemical properties of iron molybdenum catalyst synthesized with different mechanochemical experiment conditions including the number ratio of large balls to small balls, the quality ratio of agate balls to raw materials and ball milling time, have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, N2 physical absorption, X-ray photoelectron spectroscopy (XPS), etc. The catalytic performance of iron molybdenum samples in the oxidation of methanol to formaldehyde also has been evaluated in a self-built fixed-bed micro-reactor. Results demonstrate that iron molybdenum catalyst prepared by small balls shows the highest formaldehyde yield (95.2%) than the rest samples. With the increasing quality ratio of balls to materials, the phase composition of MoO3/Fe2(MoO4)3 from iron molybdenum catalyst firstly goes down and then goes up, which has close correlation with the formaldehyde selectivity. The catalyst samples prepared under ball grinding time of 30–120 min, show the typical iron molybdenum catalyst diffraction peaks, and the further extension of ball grinding time has no obvious influence on the crystal structure of iron molybdenum catalyst. The samples prepared with ball grinding time of 120 min, has the highest formaldehyde selectivity (97.56%), which could be due to the increasing content of Fe2(MoO4)3 and the improved uniformity of particles with the increasing ball grinding time.

Effect of pH, Acid and Thermal Treatment Conditions on Co/CNT Catalyst Performance in Fischer–Tropsch Reaction

Multiwalled carbon nanotubes (CNT) supported cobalt oxide was prepared as a catalyst by strong electrostatic adsorption (SEA) method. The CNT support was initially acid- and thermal-treated in order to functionalize the support to uptake more Co clusters. The Co/CNT were characterized by a range of analytical methods including transmission electron microscopy (TEM), temperature programmed reduction with hydrogen (H2-TPR), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic absorption spectroscopy (AAS), Zeta sizer particle size analysis and Brunauer–Emmett–Teller (BET) surface area analysis. TEM images showed cobalt particles were highly dispersed and impregnated at both exterior and interior walls of the CNT support with a narrow particle size distribution of 6–8 nm. In addition, the performance of the synthesized Co/CNT catalyst was tested using Fischer–Tropsch synthesis (FTS) reaction which was carried out in a fixed-bed micro-reactor. H2-TPR profiles indicated the lower reduction temperature of 420 °C was required for the FTS reaction. The study revealed that cobalt is an effective metal for Co/CNT catalysts at pH 14 and at 900 °C calcination temperature. Furthermore, FTS reaction results showed that CO conversion and C5+ selectivity were recorded at 58.7% and 83.2% respectively, which were higher than those obtained using a Co/CNT catalyst which pre-treated at a lower thermal treatment temperature and pH.

Effect of Quinoline on Hydrodesulfurization and Hydrogenation on Bi- and Trimetallic NiMo(W)/Al2O3 Hydrotreating Catalysts

The effect of quinoline on the hydrodesulfurization and hydrogenation activities of bi- and trimetallic NiMo(W)/Al2O3 hydrotreating catalysts obtained using Keggin heteropoly acids H4SiMo3W9O40, H4SiMo12O40, and H4SiW12O40 (denoted as SiMo3W9, SiMo12, and SiW12, respectively) and a mixture of two monometallic heteropoly acids (SiMo12 and SiW12) was studied. The catalytic properties were determined in a fixed-bed microreactor in hydrotreating of model feedstock containing dibenzothiophene and naphthalene and of the same feedstock with the addition of quinoline. The trimetallic NiMoW/Al2O3 sample based on the mixed SiMo3W9 heteropoly acid exhibited 1.5 times higher catalytic activity in all the reactions studied compared to its analog prepared from a mixture of SiMo12 and SiW12 heteropoly acids with the same metal ratio. The trimetallic NiMoW/Al2O3 catalyst based on the mixed SiMo3W9 heteropoly acid surpassed in the activity the NiMo/Al2O3 sample and was more resistant to the inhibiting effect of quinoline than its analog prepared from a mixture of the two heteropoly acids. The correlations of the inhibiting effect of quinoline with the morphology of the active phase particles and the content of promoted active sites Ni(Mo)WS in the bi- and trimetallic NiMo(W)/Al2O3 catalysts were found.

Effects of Cobalt Loading, Particle Size, and Calcination Condition on Co/CNT Catalyst Performance in Fischer–Tropsch Reactions

The strong electrostatic adsorption (SEA) method was applied to the synthesis of a cobalt (Co) catalyst on a multi-walled carbon nanotube (CNT) support. In order to uptake more of the cobalt cluster with higher dispersion, the CNT was functionalized via acid and thermal treatment. The Co/CNT catalyst samples were characterized by a range of methods including the Brunauer–Emmet–Teller (BET) surface area analyzer, transmission electron microscopy (TEM), X-ray powder diffraction (XRD) analysis, atomic absorption spectroscopy (AAS), and H2-temperature programmed reduction (H2-TPR) analysis. The data from the TEM images revealed that the catalyst was highly dispersed over the external and internal walls of the CNT and that it demonstrated a narrow particle size of 6–8 nm. In addition, the data from the H2-TPR studies showed a lower reduction temperature (420 °C) for the pre-treated catalyst samples. Furthermore, a Fischer–Tropsch synthesis (FTS) reaction was chosen to evaluate the Co/CNT catalyst performance by using a fixed-bed microreactor at different parameters. Finally finding the optimum value of the cobalt loading percentage, particle size, and calcination conditions of Co/CNT catalyst resulted in a CO conversion and C5+ selectivity of 58.7% and 83.2%, respectively.

Preparation of Iron-cobalt-cerium Heterogeneous Nano-catalysts to Produce Light Hydrocarbons from Synthesis Gas

Nowadays, due to the decline in oil supplies on the one hand and raising the price of petroleum, on the other hand, countries have led to other sources of fuel and energy. The use of methods such as the production of light hydrocarbons from synthesis gas is highly regarded by the Fischer-Tropsch process, in these countries. This process is performed by heterogeneous catalysts, which consist of two parts. The first part is a catalyst support (generally porous and made of silica) and the second is an active phase, which is generally made of metal. In fact, the catalyst is the heart of Fischer -Tropsch process. In this study, iron-cobalt-cerium tri-metallic nano-catalyst based on silica was prepared by the wet impregnation method. The catalyst was tested in a fixed bed micro-reactor and a wide range of products was analyzed by GC technique. By increasing temperature, the CO conversion was increased and the efficiency of products was improved. Finally, the structure of nano-catalyst was characterized using the technique of scanning electron microscopy (SEM) to realize the particle size and surface properties of the catalyst.

Heterogeneous hydroconversion of levulinic acid over silica-supported Ni catalyst

Silica-supported Ni catalyst (6.6 wt% Ni) was prepared and tested in solvent-free hydroconversion of levulinic acid (LA) using flow-through fixed-bed tube-type microreactor at 250 and 275 °C in the pressure and space time range of 1–30 bar and 0.1–1.0 gcat g LA −1 h, respectively. The catalyst was characterized by XRD, adsorption/desorption N2 isotherms, temperature-programmed H2-reduction (H2-TPR), FT-IR spectra of adsorbed pyridine (Py), and temperature-programmed H2 desorption (H2-TPD). At 250 °C and 1 bar total pressure LA was dehydrated to α-angelica lactone (AL) intermediate that was hydrogenated to γ-valerolactone (GVL). At space time 0.25 gcat g LA −1 h 82% GVL selectivity was achieved at virtually full LA conversion. The GVL became partially converted to pentanoic acid (PA). At longer space time, 1.0 gcat g LA −1 h, the PA selectivity increased to 37%. At pressure > 1 bar the favored reaction of GVL was the hydrogenolysis of its ester bond and dehydration of the intermediate 1,4-pentanediol (1,4-PD) to 2-methyltetrahydrofuran (2-MTHF). At 250 °C and 30 bar the yield of 2-MTHF was 56 mol%. The product distribution is controlled by the relative activity of the Ni/SiO2 catalyst in the hydrogenolysis of the GVL C–O bonds.

A Research on Preparation and Application of the Monolithic Catalyst with Interconnecting Pore Structure

In recent years, the monolithic material has been developed increasingly in the high performance liquid phase field, and it could also be applied in the field of catalyst, as a monolithic catalyst carrier, since it has a large specific surface area, and could be customized based on the mould. The monolithic catalyst is characterized with many advantages such as low bed pressure, high physical efficiency and small amplification effect. The most impotant part refers to the preparation of copper-based catalyst. The impregnation method is used to produce CuO-ZnO monolithic catalyst and CuO-ZnO-ZrO2 monolithic catalyst with the prepared monolithic silica-alumina carrier. The fixed bed microreactor is used to investigate the effect of copper-based catalyst on the process in which carbon dioxide is used to produce methanol through hydrogenation. The metal salt is added into the sol-gel process, which could form the M-O-Si bond, thus make the metal-containing catalytic material obtain good mechanical strength, and make it possible to be introduced into the acidic center generally. The metal-containing catalytic material carrier also has macropores and mesopores. The presence of large pores could make the molecular mass transfer more effective, while the presence of mesopores could increase the specific surface area of the material. In this paper, the experimental study has been conducted on the production of methanol through hydrogenation of CO2 under different catalysts, to mainly investigate the effect of catalysts with different catalytic performance on the reaction.

Effect of alkaline earth metal doping on the catalytic performance of cobalt-based spinel composite metal oxides in N2O decomposition

A series of cobalt-based spinel composite metal oxides doped with alkaline earth metals, viz., MxCo3-xO4 (M = Mg, Ca, Sr and Ba; x = 0, 0.1, 0.3, 0.5, 0.7 and 0.9), were prepared by the coprecipitation method and characterized by XRD, SEM, nitrogen sorption, H2-TPR, O2-TPD-MS and XPS; the effect of alkaline earth metal doping on the catalytic performance of MxCo3-xO4 composites in N2O decomposition was investigated in a fixed bed micro-reactor. The results showed that after doping with the alkaline earth metals, the particle size of MxCo3-xO4 catalysts is decreased, accompanying with an increase in the specific surface area and the amount of surface adsorbed oxygen and Co2+ species. Meanwhile, the redox performance and catalytic activity of MxCo3-xO4 in N2O decomposition are also greatly enhanced. Under the conditions of 0.68% N2O, 3% O2 and Ar as balance gas, the Sr0.7Co2.3O4 catalyst doped with Sr (x = 0.7) exhibits highest activity in N2O decomposition; the reaction temperatures where the N2O conversion reaches 10% and 95% are as low as 312 and 451°C, respectively.

Effect of Cobalt Catalyst Confinement in Carbon Nanotubes Support on Fischer-Tropsch Synthesis Performance

Pre-treating the multi-walled carbon nanotubes (CNTs) support by refluxing in 35 vol% nitric acid followed by heating at the temperature of 600 to 900 °C resulted in the formation of defects on the CNTs. Increasing the temperature of the pre-treatment of the CNTs from 600 °C to 900 °C, enhanced the fraction of cobalt-oxide nanoparticles encapsulated in the channels of CNTs from 31% to 70%. The performance of Co/CNTs in Fischer-Tropsch synthesis (FTS) was evaluated in a fixed-bed micro-reactor at a temperature of 240 °C and a pressure of 2.0 MPa. The highest CO conversion obtained over Co/CNTs.A.900 was 59% and it dropped by ~3% after 130 h of time-on-stream. However, maximum CO conversion using Co/CNTs.A.600 catalysts was 28% and it decreased rapidly by about 54% after 130 h of time-on-stream. These findings show that the combined acid and thermal pre-treatment of CNTs support at 900 °C has improved the stability and activity of the Co/CNTs catalyst in FTS.

Catalytic pyrolysis of lignin with red mud derived hierarchical porous catalyst for alkyl-phenols and hydrocarbons production

Red mud (RM) was activated by a feasible digestion-precipitation method followed by calcination at 600 °C (denoted as ACRM), which was used as a novel catalyst during the thermal degradation of the lignin. The prepared catalyst was then applied to the lignin derived from agricultural waste using a vertical fixed-bed microreactor between 350–650 °C. The texture characteristics of the activated RM were characterized by XRF, FTIR, XRD, TEM, SEM-EDS, NH3-TPD, and the N2 isothermal absorption method. The analysis results indicated that the ACRM catalyst possessed a high specific surface area, hierarchical porosity, acidity and active metal oxides (Fe2O3, Al2O3, and TiO2). Maximum bio-oil yield (25 wt.%) was observed at 550 °C, however, the bio-oil yield exhibited an overall declined trend in comparison to the non-catalytic pyrolysis at the corresponding pyrolysis temperatures. The relative contents of alkyl-phenols and the hydrocarbons significantly increased using the ACRM catalyst at 550 °C, which was attributed to the strengthening of dehydroxylation, demethylation, demethoxylation, and alkylation reactions. The study demonstrated the ACRM could be used as a promising catalyst for upgrading the pyrolysis vapours of lignin with considerable economic and ecological benefits.

Nanocomposite material like advanced sorbent materials for carbon dioxide capture

In this work carbonized rice husk was used as carbon-based solid matrix in the preparation of composite materials modified with Fe3O4 particles. Aim of this study is to exploit the advantages and shortcomings of using a real biomass as starting material for the preparation of sorbents for CO2 capture applications. Sorption capacity of the obtained composite materials was tested on fixed-bed microreactor.

Effect of calcination temperature on low-temperature NH3-SCR activity and the resistance of SO2 with or without H2O over Fe–Mn–Zr catalyst

Abstract A novel Fe–Mn–Zr was prepared by co-precipitation method and calcined at different temperature. The NO removal capacity, N2 selectivity and SO2 resistance with or without H2O over Fe–Mn–Zr were investigated in a fixed-bed microreactor. The results showed that the catalysts calcined at 400–600 °C exhibit 100% NO removal efficiency in the range of 170–360 °C. FMZ-500 shows a better tolerance to both 100 and 200 ppm SO2 than other samples and excellent resistance to H2O and can achieve over 93% NO removal efficiency in the presence of SO2 and H2O. FMZ-500 catalyst can completely recover NO removal capacity when SO2 and H2O shut off. When Fe–Mn–Zr is calcined at 700 and 800 °C, NO removal efficiency at 170 °C are 90% for FMZ-700 and 35% for FMZ-800 and their resistances to SO2 are very poor. When Fe–Mn–Zr is calcined at 400, 500 and 600 °C, MnO2, Mn2O3 and Fe2O3 are homogeneously dispersed and exist mainly in an amorphous state as well as similar reduction properties. When the calcination temperature increases to 800 °C, the crystallinity of oxides significantly increases and reduction temperatures shift from 318 and 413 °C to 420 and 478 °C. High temperature calcination causes the decrease of surface area and Lewisacid sites, corresponding to low NH3 adsorption.

Characterization and catalytic behavior of EDTA modified silica nanosprings (NS)-supported cobalt catalyst for Fischer-Tropsch CO-hydrogenation

The effect of ethylene diamine tetraacetic acid (EDTA) modification on the physico-chemical properties and catalytic performance of silica nanosprings (NS) supported cobalt (Co) catalyst was investigated in the conversion of syngas (H2 + CO) to hydrocarbons by Fischer-Tropsch synthesis (FTS). The unmodified Co/NS and modified Co/NS-EDTA catalysts were synthesized via an impregnation method. The prepared Co/NS and Co/NS-EDTA catalysts were characterized before the FTS reaction by BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), differential thermal analysis (DTA) and thermogravimetric analysis (TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. FTS was carried out in a quartz fixed-bed microreactor (H2/CO of 2:1, 230°C and atmospheric pressure) and the products trapped and analyzed by GC-TCD and GC-MS to determine CO conversion and reaction selectivity. The experimental results indicated that the modified Co/NS-EDTA catalyst displayed a more-dispersed phase of Co3O4 nanoparticles (10.9%) and the Co3O4 average crystallite size was about 12.4 nm. The EDTA modified catalyst showed relatively higher CO conversion (70.3%) and selectivity toward C6–18 (JP-8, Jet A and diesel) than the Co/NS catalyst (C6–14) (JP-4).

Comparative evaluation of autothermal reforming of biogas into synthesis gas over bimetallic Ni[sbnd]Re/Al2O3 catalyst in fixed-bed and coated-wall microreactors: A computational study

Autothermal reforming reaction of biogas over a novel NiRe/Al2O3 catalyst in a coated-wall microreactor was numerically investigated and compared with that in a fixed-bed microreactor having the same catalyst loading. The effects of inlet concentrations of O2 and H2O as well as temperature on the reaction effectiveness within both microreactors were, for the first time, assessed to determine an optimal condition, which yielded complete CH4 and CO2 conversions, H2/CO ratio of around one and minimal hot spot formation. Such an optimal condition was then used to study the effect of inlet reactant Reynolds number on the reactor performance. Higher CH4 and CO2 conversions, lower H2O production and less hot spot formation were noted in the case of the coated-wall microreactor. The optimal condition occurred at CH4:CO2:O2:H2O ratio of 39:26:30:5% (v/v) and inlet temperature of 740 °C. The performance of the coated-wall microreactor was superior to that of the fixed-bed microreactor in all cases.

Optimizing the Preparation Conditions of Silica Supported Fe-Co-Ce Ternary Catalyst for the Fixed-bed Fischer-Tropsch Synthesis: Taguchi Experimental Design Approach

Using wet impregnation method, a novel ternary system of silica supported Fe-Co-Ce catalyst was prepared. Preparation conditions such as impregnation time and temperature, drying time and temperature, were optimized by the L9 Taguchi experimental design to achieve a light olefin selective catalyst with maximum CO conversion in a fixed bed micro-reactor. It was found that the best conditions to maximize the responses were obtained at 4h impregnation time, 60°C impregnation temperature, 6h drying time, 90°C drying temperature and 350°C of reaction’s temperature. Characterization of the optimal catalyst precursors and calcined samples before, and after the Fischer-Tropsch reaction was carried out using various techniques.