Tek aşamalı CO2 dönüşümü ile dimetil eter üretimini destekleyen süreç yoğunlaştırma stratejileri

This thesis investigates the intensification of the direct one-step hydrogenation of CO2 to dimethyl ether (DME), a value-added fuel and chemical, through advanced bifunctional catalyst design and in-situ H2O removal. The primary objective was to overcome the thermodynamic limitations imposed by H2O generation during the reverse water-gas shift (RWGS) and methanol (MeOH) dehydration reactions. While γ-Al2O3 is widely used for methanol dehydration, it suffers from activity loss due to competitive adsorption of H2O. Addition of phosphotungstic acid (PTA) to γ-Al2O3 enriches surface Brønsted acid sites, which doubles the DME productivity and suppresses byproduct formation by favoring a direct associative reaction mechanism. In sorption-free benchmark tests at 245 °C and 3.0 MPa, the 30 wt.% PTA/γ-Al2O3 catalyst demonstrated superior stability during a 72-hour time-on-stream test. Subsequently, the process was intensified via integrating a Zeolite 3A (Z3A) adsorbent. A parametric study identified that peak productivity (2.1 × 10−2 kgDME kgcat-1 h-1) was favored at a GHSV of 7000 h-1 with an adsorbent loading of 6 g, utilizing pressure swing adsorption (PSA) for rapid adsorbent regeneration. Finally, the spatial configuration of the reactor bed was optimized by separating the Z3A from CZA and shifting it to the acidic catalyst bed. At 7000 h-1, this split-bed configuration improved the DME/MeOH selectivity to 62% compared to 25% for the mixed bed, effectively decoupling the metallic and acidic functions and increasing the DME productivity to 2.5 × 10−2 kgDME kgcat-1 h-1. This work provides a comprehensive set of novel information at the catalyst and reactor scales to overcome the critical bottlenecks of valorzing CO2 to DME.