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The direct synthesis of dimethyl ether (DME) is an ideal process to achieve the environmental objective of CO2 conversion together with the economic objective of DME production. The effect of the reaction conditions (temperature, pressure, space time) and feed composition (ternary mixtures of H2 + CO + CO2 with different CO2/CO and H2/COx molar ratios) on the reaction indices (COx conversion, product yield and selectivity, CO2 conversion) has been studied by means of experiments carried out in a fixed-bed reactor, with a CuO-ZnO-MnO/SAPO-18 catalyst, in order to establish suitable ranges of operating conditions for enhancing the individual objectives of CO2 conversion and DME yield. The optimums of these two objectives are achieved in opposite conditions, and for striking a good balance between both objectives, the following conditions are suitable: 275–300 °C; 20–30 bar; 2.5–5 gcat h (molC)−1 and a H2/COx molar ratio in the feed of 3. CO2/CO molar ratio in the feed is of great importance. Ratios below 1/3 are suitable for enhancing DME production, whereas CO2/CO ratios above 1 improve the conversion of CO2. This conversion of CO2 in the overall process of DME synthesis is favored by the reverse water gas shift equation, since CO is more active than CO2 in the methanol synthesis reaction.
Ainara Ateka; Javier Ereña; Miguel Sánchez-Contador; Paula Perez-Uriarte; Javier Bilbao; Andrés T. Aguayo. Capability of the Direct Dimethyl Ether Synthesis Process for the Conversion of Carbon Dioxide. Applied Sciences 2018, 8, 677 .
AMA StyleAinara Ateka, Javier Ereña, Miguel Sánchez-Contador, Paula Perez-Uriarte, Javier Bilbao, Andrés T. Aguayo. Capability of the Direct Dimethyl Ether Synthesis Process for the Conversion of Carbon Dioxide. Applied Sciences. 2018; 8 (5):677.
Chicago/Turabian StyleAinara Ateka; Javier Ereña; Miguel Sánchez-Contador; Paula Perez-Uriarte; Javier Bilbao; Andrés T. Aguayo. 2018. "Capability of the Direct Dimethyl Ether Synthesis Process for the Conversion of Carbon Dioxide." Applied Sciences 8, no. 5: 677.
A kinetic model of 11 lumps (dimethyl ether, methanol, water, ethylene, propylene, butenes, C2-C4 paraffins, C5+ hydrocarbons, BTX aromatics, methane and CO) has been determined for the reaction of DME to olefins (DTO process) over a HZSM-5 zeolite catalyst (SiO2/Al2O3 = 280) agglomerated with boehmite. The experiments have been carried out under a slightly above than at 1.5 bar in an isothermal fixed bed reactor under a wide range of operating conditions: 598-673 K; space time, 0.2-6 gcat h molC-1; feed, pure DME and co-fed with He, methanol and water. The model characterizes the effect of the reaction conditions (temperature, space time and feed composition) over the product distribution at zero time on stream. The kinetic constant of DME conversion to olefins (at 623 K) is 20 times greater than that of methanol conversion. This result and the non-existence of the methanol dehydration step are the main differences between both processes. These differences have a great impact on the advance of the reaction and on the yield and distribution of product fractions.
Paula Pérez-Uriarte; Ainara Ateka; Andres Tomas Aguayo; Ana G. Gayubo; Javier Bilbao. Kinetic model for the reaction of DME to olefins over a HZSM-5 zeolite catalyst. Chemical Engineering Journal 2016, 302, 801 -810.
AMA StylePaula Pérez-Uriarte, Ainara Ateka, Andres Tomas Aguayo, Ana G. Gayubo, Javier Bilbao. Kinetic model for the reaction of DME to olefins over a HZSM-5 zeolite catalyst. Chemical Engineering Journal. 2016; 302 ():801-810.
Chicago/Turabian StylePaula Pérez-Uriarte; Ainara Ateka; Andres Tomas Aguayo; Ana G. Gayubo; Javier Bilbao. 2016. "Kinetic model for the reaction of DME to olefins over a HZSM-5 zeolite catalyst." Chemical Engineering Journal 302, no. : 801-810.
The effect of the catalyst properties, particularly matrix acidity and its properties, has been studied in the transformation of dimethyl ether (DME) to light olefins. The catalysts used were prepared by agglomerating HZSM-5 zeolite with a different SiO2/Al2O3 ratio (30, 80, and 280) with bentonite or boehmite as a binder and α-Al2O3 as inert filler. The experiments have been carried out in a fixed bed reactor, under the following reaction conditions: 350 and 400 °C; space-time, 0.4 gzeolite h molC–1; time on stream, 4 h. The lower content of H2O in the reaction medium compared to that of the methanol transformation explains the advancement on the reaction scheme (with the transformation of olefins in other hydrocarbons) and more rapid deactivation by coke, which advises the use of catalysts with lower acidity and shaping the catalyst particles with a porous structure that attenuates the blocking of acid sites. The acidic properties of the zeolite have a significant impact on the DME conversion, yield and selectivity of light olefins, and catalyst stability. A good compromise of these rates is obtained with a catalyst prepared with HZSM-5 zeolite of moderate acidity (SiO2/Al2O3 = 280) and using boehmite as binder. In the calcination of catalyst the boehmite is converted into γ-Al2O3, whose weak acidity and mesoporous structure contribute to increase activity and stability of the catalyst.
Paula Pérez-Uriarte; Mónica Gamero; Ainara Ateka; Marta Díaz; Andres Tomas Aguayo; Javier Bilbao. Effect of the Acidity of HZSM-5 Zeolite and the Binder in the DME Transformation to Olefins. Industrial & Engineering Chemistry Research 2016, 55, 1513 -1521.
AMA StylePaula Pérez-Uriarte, Mónica Gamero, Ainara Ateka, Marta Díaz, Andres Tomas Aguayo, Javier Bilbao. Effect of the Acidity of HZSM-5 Zeolite and the Binder in the DME Transformation to Olefins. Industrial & Engineering Chemistry Research. 2016; 55 (6):1513-1521.
Chicago/Turabian StylePaula Pérez-Uriarte; Mónica Gamero; Ainara Ateka; Marta Díaz; Andres Tomas Aguayo; Javier Bilbao. 2016. "Effect of the Acidity of HZSM-5 Zeolite and the Binder in the DME Transformation to Olefins." Industrial & Engineering Chemistry Research 55, no. 6: 1513-1521.