Methanol synthesis in a three‐phase catalytic bed under nonwetted condition

Abstract

To overcome the heat removal problem encountered in methanol synthesis at high syngas concentrations in the gas phase, a three‐phase nonwetted catalytic system was established by introducing an inert liquid medium into a fixed‐bed reactor. To form a repellent interface between the liquid and the catalyst, the catalyst was modified into hydrophobic, while the liquid medium was chosen as a room temperature ionic liquid with hydroxyl groups. The liquid‐solid contact angle was measured to be 115°, and only 20% of the catalyst external surface was wetted by the liquid. Under three‐phase condition, the reaction rate was measured to be 60%–70% of gas‐phase reaction, while it was merely 10%–20% for the fully wetted catalyst. From the resistance analysis on the mass transfer and reaction steps, the overall reaction rate is expected to increase further if the surface could be more wet proofed. © 2016 American Institute of Chemical Engineers AIChE J, 63: 226–237, 2017

Flow regimes in a gas–liquid–solid three‐phase moving bed

“…It is necessary to optimize trickle bed reactors according to the characteristics of targeted reactions. For instance, for reactions where gas is reactant and liquid is product, such as Fischer–Tropsch synthesis, 5 particle wettability can be modified to decrease the gas‐phase mass transfer resistance 6 . While for reactions in which the liquid phase is the reaction control phase, such as heavy oil hydrogenation, 7 gas–liquid distributors can be optimized to realize the uniform distribution of liquid 4 .…”

Dicationic Imizadolium‐Based Tetrafluoroborate Ionic Liquids: Synthesis and Hydrothermal Stability Study

“…Six DILs with imidazolium cation and [BF 4 ] − anion were synthesized and determined by FTIR and NMR, and their thermal stability was investigated by TGA. Our previous study has proved that hydrophilic ionic liquids can be used as an inert solvent for three‐phase methanol synthesis [14a] . In this reaction, the optimum temperature is about 240 °C, and water, is produced due to reaction between CO 2 and H 2 so the long‐term hydrothermal stability of DILs was studied under 240 °C and 3 MPa, which is close to the conditions of methanol synthesis.…”

A Surface-Cofunctionalized Silica Supported Palladium Catalyst for Selective Hydrogenation of Nitrile Butadiene Rubber with Enhanced Catalytic Activity and Recycling Performance

“…Pd/N–SiO 2 has the most weight loss probably because Pd active sites have an attraction with −CN groups and the polar EDAS also produced a polar attraction with the NBR/HNBR . Pd/C–SiO 2 has the minimal weight loss, probably due to the nonpolar and hydrophobic surface having a repulsive force with polar NBR/HNBR molecules and facilitating their desorption from the catalyst. − …”

“…As illustrated in Scheme , because the −CN bonds could have an attraction with Pd NPs and the polar amino groups on the support also might enhance the polar attraction with the polar NBR/HNBR macromolecules, thus HNBR could not easily desorb from the Pd/N–SiO 2 and still occupy the Pd active centers. The activity of the used Pd/N–SiO 2 catalyst could be restored only after washing with a large amount of solvent several times to elute the polymers and re-expose the active sites, − or else the recycling performance would be significantly reduced due to the coverage of active metal sites. For the surface-cofunctionalized silica-supported palladium catalyst, the CH 3 could improve its surface hydrophobicity and then reduce surface polarity, and the repulsive force between the polar CN bonds and the nonpolar methyl groups could result in the acceleration of the desorption of HNBR macromolecules from the Pd/C–N–SiO 2 catalyst after the hydrogenation of CC.…”