Controlled methylamine synthesis in a membrane reactor featuring a highly steam selective K⁺-LTA membrane

authored by

Felix Rieck genannt Best, Alexander Mundstock, Hannes Richter, Patrick A. Kißling, Karen D.J. Hindricks, Aisheng Huang, Peter Behrens, Jürgen Caro

Abstract

Water permeation through a hydrophilic zeolite membrane can be used to promote reactions under equilibrium controlled conditions through the in situ removal of the by-product water. In the methylamine synthesis, mono- (MMA), di- (DMA) and trimethylamine (TMA) are formed by the successive methylation of ammonia with methanol (MeOH) over a mildly acidic catalyst. The methylamine yield can be increased through selective water extraction from the reactor through a membrane. Since both reactants and water have similar molecular kinetic diameters below 3.7 Å, because of the limited steam selectivity of the commonly used hydrophilic Na-LTA membrane (zeolite 4A), not only water has been removed. Therefore, in this work a K-LTA membrane, which was obtained by ion exchange with a reduced pore window diameter of 3 Å and thus with a higher water selectivity, was used in the membrane-supported methylamine synthesis. When replacing the Na-LTA with the K-LTA membrane, the H₂O/MeOH mixed gas separation factor increases up to 1100 and the H₂O/NH₃ separation could also be improved. This in turn leads to an overall boost of the higher methylated amines DMA and TMA in methylamine synthesis. When using the narrow-pore aluminosilicate catalyst H-SSZ-13 with CHA structure, the application of the K-LTA membrane increases the share of the industrially desired product DMA from 51% without membrane to 74% with slightly increased conversion. When using the large-pore catalyst H-MOR, the thermodynamically most stable product TMA can be formed and the selectivity was increased from 35% without membrane to 41% with the K-LTA membrane.

Organisation(s)

Institute of Physical Chemistry and Electrochemistry
Institute of Inorganic Chemistry
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Laboratory of Nano and Quantum Engineering

External Organisation(s)

Fraunhofer Institute for Ceramic Technologies and Systems (IKTS)
East China Normal University
South China University of Technology

Type

Article

Journal

Microporous and Mesoporous Materials

Volume

337

ISSN

1387-1811

Publication date

05.2022

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanics of Materials

Electronic version(s)

https://doi.org/10.1016/j.micromeso.2022.111920 (Access: Closed)