Functionalized montmorillonite supported rhodium complexes: Efficient catalysts for carbonylation of methanol

• Two new montmorillonite anchored Rh catalyst were synthesized and characterised.
• The catalysts were used in the carbonylation of methanol and recycled upto 3rd run.
• Conversion upto 99.9% was obtained without formation of methylacetate as byproduct.

The catalyst precursors, [Rh(CO)2Cl-ligand(L)-APTMS-montmorillonite] (1a and 1b, where, a and b correspond to ligand (L)-APTMS-montmorillonite for ligands L = Quinoline-2-carboxylic acid (L1) and Quinoline-8-carboxylic acid (L2) respectively; APTMS = (3-aminopropyl)-trimethoxysilane), have been synthesised. The montmorillonite was activated by treating with formic acid under controlled condition to increase the surface area and pore volume prior to functionalization by APTMS and subsequent anchoring with the ligands. 1a and 1b were characterized by CHN, FT-IR, powder XRD, N2-sorption and SEM-EDX analysis. The efficacy of the catalysts was evaluated in carbonylation of methanol to acetic acid and found to exhibit catalytic conversion up to 99.9%. The catalysts were recovered and reused for several runs without any significant loss of catalytic efficiency.

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