Study of deactivation in mesocellular foam carbon (MCF-C) catalyst used in gas-phase dehydrogenation of ethanol

Mesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 °C significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.

Study of Deactivation in Mesocellular Foam Carbon (MCF-C) Catalyst Used in Gas-Phase Dehydrogenation of Ethanol

Mesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 ºC significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.

Synthesis of tert-amylbenzene for side-chain alkylation of cumene catalyzed by a solid superbase

The side-chain alkylation of cumene and ethylene over a solid superbase catalyst K/KOH/γ-Al2O3 is investigated. The effects of the reaction temperature, pressure, and time on the conversion of cumene and selectivity of tert-amylbenzene (TAB) are discussed. The experimental results show that the conversion of cumene to tert-pentylbenzene increases with the increase in reaction temperature and ethylene pressure. The catalytic reaction has certain operational flexibility in terms of the reaction temperature, pressure, and time. In addition, the catalytic reaction can achieve directional conversion. The optimum operating conditions are obtained using a single factor test. The conversion of cumene is 99.8% and the selectivity toward TAB is 97.9% under catalyst concentration of 4 wt%, reaction temperature of 55°C, reaction pressure of 0.45 MPa, and reaction time of 30 min. The deactivation of catalyst is mainly caused by oxygen and water in the raw material.

Pengembangan katalis Ni/Al2o3 untuk steam reforming tar hasil gasifikasi

The development of catalysts Ni/Al2O3 for steam reforming gasification tar This research studied the secondary tar removal in gasification technology through catalytic toluene steam reforming reactions. The objective of this study was to obtain a nickel catalyst that has good performance for steam reforming of tar (toluene) by selecting the -Al2O3 or -Al2O3 supports, and adding promoter to inhibit deactivation due to coke formation. The performance of the catalyst is determined from the activity test in a fixed bed reactor at a temperature of 700 oC, atmospheric pressure, Time on Stream (TOS) 10 hours and stability test indicated by XRD and TGA. The catalyst showed the best performance was the Ni/-Al2O3 catalyst with the average of toluene conversion of 96%. The addition of 2% and 5% by weight of CaO decreased the catalytic activity. Although it proved to inhibit the formation of coke, it did not reduce the rate of deactivation of catalyst. The XRD analysis showed that the Ni/-Al2O3 after 10 hours in operation did not undergo any phase changes, thus the catalyst was still stable. Keywords: tar cracking, steam reforming, nickel catalyst, toluene conversion, stability. AbstrakPenelitian ini merupakan suatu bagian dalam pengembangan teknologi penghilangan tar gasifikasi secara sekunder dengan cara perengkahan katalitik menggunakan reaksi steam reforming toluen. Tujuan penelitian ini adalah mendapatkan katalis berbasis nikel yang memiliki kinerja yang baik untuk steam reforming tar (toluen) dengan memilih penyangga -Al2O3 atau -Al2O3, dan menambah promotor CaO untuk menghambat deaktivasi akibat pembentukan arang. Kinerja katalis ditentukan dari uji aktivitas di dalam reaktor fixed bed pada temperatur 700 oC, tekanan atmosferik, selama 10 jam dan uji stabilitas yang diindikasikan menggunakan XRD dan TGA. Hasil pengujian aktivitas memperlihatkan bahwa katalis Ni/-Al2O3 menghasilkan aktivitas yang paling baik dengan rata - rata konversi toluen 96%. Penambahan promotor CaO 2% dan 5% berat menurunkan aktivitas katalis Ni/-Al2O3 dan menghambat pembentukan arang, tetapi tidak mengurangi laju deaktivasi katalis. Hasil XRD katalis Ni/-Al2O3 setelah reaksi 10 jam menunjukkan tidak adanya perubahan fasa dari -Al2O3 ke -Al2O3, yang berarti katalis masih tetap stabil.Kata Kunci: perengkahan tar, katalis nikel, konversi toluen, stabilitas.

Deactivation Characteristics of SCR Catalyst at Different Stages in Coal-Fired Flue Gas

Through analyzing the impact of the factors of catalyst deactivation, different factors are classified according to timeliness characteristics. In this research, experiments were made under the condition of coal combustion flue gas on a coal-fired boiler to study the characteristics of the early deactivation of the SCR catalyst. Analysis shows that the main cause of early deactivation of catalyst is chemical poisoning (mainly alkali metal) and pores clogging on the surface of the catalyst. While the main cause of long-term deactivation is deeper chemical poisoning, pores clogging and the chemical form changes of elements on the surface of the catalyst. Through analyzing the influence of the factors of catalyst deactivation, separate factors are classified according to timeliness characteristics. This research provides a strong fundamental support to clear the deactivation mechanism of the SCR catalyst.

HDO REACTION OF THF USING Pt/γ-AL2O3 CATALYST ENRICHED BY ALUMINA : EFFECT OF TEMPERATURE TO PRODUCT DISTRIBUTION, RATE OF REACTION AND DEACTIVATON OF CATALYST

<p>Effect of temperature variation to product distribution, rate and deactivation of catalyst of tetrahydrifuran hydrodeoxygenation have been conducted using Pt/gAl₂O₃ with aluminum enrichmen. Reaction was conducted by flow system. Product of reaction were analyzed as propane (C₃) and buthene derivate (C₄). At 350ºC, reaction product and rate constant were optimum. At higher temperature, product distribution was shift from C₄ to C₃. Lowering pore size catalyst, surface area and acidity of catalyst were responsible to catalyst deactivation. Deactivation process was follow exponential regression.</p>

HDO REACTION OF THF USING Pt/γ-AL2O3 CATALYST ENRICHED BY ALUMINA : EFFECT OF TEMPERATURE TO PRODUCT DISTRIBUTION, RATE OF REACTION AND DEACTIVATON OF CATALYST

<p>Effect of temperature variation to product distribution, rate and deactivation of catalyst of tetrahydrifuran hydrodeoxygenation have been conducted using Pt/gAl₂O₃ with aluminum enrichmen. Reaction was conducted by flow system. Product of reaction were analyzed as propane (C₃) and buthene derivate (C₄). At 350ºC, reaction product and rate constant were optimum. At higher temperature, product distribution was shift from C₄ to C₃. Lowering pore size catalyst, surface area and acidity of catalyst were responsible to catalyst deactivation. Deactivation process was follow exponential regression.</p>

Oxygen-containing coke species in zeolite-catalyzed conversion of methanol to hydrocarbons

Oxygen-containing coke species are identified during methanol-to-hydrocarbons reactions, and their influence on the deactivation of catalyst is investigated.