Surface hydrophobicity and acidity effect on alumina catalyst in catalytic methanol dehydration reaction

Abstract

BACKGROUNDMethanol to dimethyl ether (MTD) is considered one of the main routes for the production of clean bio‐fuel. The effect of copper loading on the catalytic performance of different phases of alumina that formed by calcination at two different temperatures was examined for the dehydration of methanol to dimethyl ether (DME).RESULTSA range of Cu loadings of (1, 2, 4, 6, 10 and 15% Cu wt/wt) on Al2O3 calcined at 350 and 550 °C were prepared and characterized by TGA, XRD, BET, NH3‐TPD, TEM, H2‐TPR, SEM, EDX, XPS and DRIFT‐Pyridine techniques. The prepared catalysts were used in a fixed bed reactor under reaction conditions in which the temperature ranged from 180–300 °C with weight hourly space velocity (WHSV) = 12.1 h‐1. It was observed that all catalysts calcined at 550 °C (γ‐Al2O3 support phase) exhibited higher activity than those calcined at 350 °C (γ‐AlOOH), and this is due to the phase support change. Furthermore, the optimum Cu loading was found to be 6% Cu/γ‐Al2O3 with this catalyst also showing a high degree of stability under steady state conditions and this is attributed to the enhancement in surface acidity and hydrophobicity.CONCLUSIONThe addition of copper to the support improved the catalyst properties and activity. For all the copper modified catalysts, the optimum catalyst with high degree of activity and stability was 6% copper loaded on gamma alumina. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Kinetic Investigation of η-Al2O3 Catalyst for Dimethyl Ether Production

“…2b which is in agreement with the kinetic model shown in Table 2. Moreover, during the reaction mechanism, water is produced which has a significant effect on the alumina catalyst deactivation, as water and methanol compete for adsorbing on the active sites of alumina catalyst with water being adsorbed more strongly [31]. It is worth noting that in our previous publication we showed that the prepared η-Al 2 O 3 has similar morphology and surface acidity of zeolite [HZSM-5(80)] which is in line with the fitted kinetic modelling as our work matched with Lu model who studied the kinetic modelling of zeolite as shown in Table 2 [10].…”

Physicochemical characterization of miscanthus and its application in heavy metals removal from wastewaters

“…Alumina can also adsorb heavy metals where its surface area can reach 369 m 2 /g [17][18][19] but again this is proving too expensive for developing countries. Alumina can also adsorb heavy metals where its surface area can reach 369 m 2 /g [17][18][19] but again this is proving too expensive for developing countries.…”

“…There are many traditional processes for removing heavy metals from wastewater depending on chemical precipitation, floatation, adsorption, ion exchange, and electrochemical deposition. Alumina can also adsorb heavy metals where its surface area can reach 369 m 2 /g [17][18][19] but again this is proving too expensive for developing countries. Researchers in developing countries suggest the use of adsorbents produced from agricultural waste materials [20] such as spent grain [21], aquatic weeds [22], egg shell [23], coal fly ash [24][25][26], rice husks [27], and polymerized onion skin [28] could become economically viable for HMR process.…”

Produce Low Aromatic Contents with Enhanced Cold Properties of Hydrotreated Renewable Diesel Using Pt/Alumina-Beta-Zeolite: Reaction Path Studied via Monoaromatic Model Compound

“…Thepublications observed on protonation of Brønstedacid sites induce hydrogen ions for rebranching and isomerisation processes in high Si/Al zeolites [10][11][12][13][14][15][16][17][18]. The previous study revealed that zeolite makes the transition metal more electrophilic, thus helps the reoxidation of metal during the reaction [19].…”

“…Hydrotreated FAME in Gas Oil ( In recent decades, hydro-isomerisation of ULSD by noble metals on acidic solid catalyst like zeolites or silica aluminates in micro-or mesopore structure was used in refineries [6][7][8][9]. Zeolite synthesis with different crystalline structure and characteristics had widely studied and, its performance was investigate using hydro-isomerisation and hydrocracking on ZSM, Y-type, H-β, SAPO and MCM for branching the high molecular weight straight-chain hydrocarbons [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Product shape selectivity mainly achieved through the crystalline pore structure and molecule size in pore diffusive diameter, but the acidity of catalyst play the main role in product distribution [13][14][15].The tuning of the acidic property of zeolite and extrudate was achieved by varying SiO 2 /Al 2 O 3 (or Si/Al) and the operating temperature.…”