The carbonylation of dimethyl ether (DME) to methyl acetate (MA) is one of the crucial steps in an indirect synthesis route of ethanol from syngas (CO+H2). The H-MOR zeolite exhibits excellent activity and selectivity at mild conditions. However, the catalyst suffers rapid deactivation due to the carbonaceous deposits on Brønsted acid sites. In this study, the deactivation kinetics for the carbonylation of DME to MA on the H-MOR zeolite was investigated. Based on the fitting results and in situ FTIR analysis, a model taking into account the composition concentration was established. This deactivation kinetic model allows simulating the concentration of different compounds in the reaction medium with time on stream under different experimental conditions. In this model, coke is considered to be derived from DME and CO. Moreover, CO remarkably accelerates the coke formation, and the effect of its concentration on the deactivation rate is quantified. The establishment of deactivation kinetics will be conductive to elucidate the coke formation mechanism and optimize the process conditions.

•θ-Fe3C(0 3 1) is the most exposed facet of Fe3C due to its thermal stability.•θ-Fe3C(0 3 1) shows high effective barriers towards CH4 formation.•CH + CH and CH2 + CH2 are the dominant chain growth pathways on θ-Fe3C(0 3 1) surface.•θ-Fe3C(0 3 1) shows the low selectivity of CH4 and the high selectivity of C2+.θ-Fe3C has been reported to play a key role in C2−C4 olefins production for Fischer−Tropsch synthesis. In this work, (0 3 1) is confirmed as the most exposed facet of θ-Fe3C due to its thermodynamic stability. Investigation on CH4 formation and C1−C1 coupling reveals that CH4 formation exhibits a high effective barrier and CH + CH and CH2 + CH2 are the dominant chain growth pathways. ΔEeff was employed to quantify the selectivity of CH4 and C2+. The high value of ΔEeff indicates the preference of C2+ formation to CH4. These results will help for the design of selective Fe-based FT catalysts.Download high-res image (61KB)Download full-size image

In the present study, a superhydrophobic polyurethane (PU) sponge with hierarchically structured surface, which exhibits excellent performance in absorbing oils/organic solvents, was fabricated for the first time through mussel-inspired one-step copolymerization approach. Specifically, dopamine (a small molecular bioadhesive) and n-dodecylthiol were copolymerized in an alkaline aqueous solution to generate polydopamine (PDA) nanoaggregates with n-dodecylthiol motifs on the surface of the PU sponge skeletons. Then, the superhydrophobic sponge that comprised a hierarchical structured surface similar to the chemical/topological structures of lotus leaf was fabricated. The topological structures, surface wettability, and mechanical property of the sponge were characterized by scanning electron microscopy, contact angle experiments, and compression test. Just as a result of the highly porous structure, superhydrophobic property and strong mechanical stability, this sponge exhibited desirable absorption capability of oils/organic solvents (weight gains ranging from 2494% to 8670%), suggesting a promising sorbents for the removal of oily pollutants from water. Furthermore, thanks to the nonutilization of the complicated processes or sophisticated equipment, the fabrication of the superhydrophobic sponge seemed to be quite easy to scale up. All these merits make the sponge a competitive candidate when compared to the conventional absorbents, for example, nonwoven polypropylene fabric.Keywords: hierarchically structured surface; mussel-inspired chemistry; oil/water separation; polydopamine; superhydrophobicity