Niobium-substituted octahedral molecular sieve (OMS-2) materials in selective oxidation of methanol to dimethoxymethane. Issue 56 (14th October 2019)

• Record Type: Journal Article
• Authors: Wasalathanthri, Niluka D.; Guild, Curtis; Nizami, Quddus A.; Dissanayake, Shanka L.; He, Junkai; Kerns, Peter; Fee, Jared; Achola, Laura; Rathnayake, Dinithi; Weerakkody, Chandima; Suib, Steven L.; Nandi, Partha
• Is Part Of: RSC advances. Volume 9:Issue 56(2019)
• Page Start: 32665
• Page End: 32673
• Publication Date: 2019-10-14
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9ra04804a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The prepared bifunctional Nb-OMS-2 catalysts are promising candidate in partial oxidation of methanol into dimethoxymethane at a lower temperature suggesting that there is an important temperature regime when forming active sites for DMM production. Abstract : Octahedral molecular sieve (OMS-2) refers to a one-dimensional 2 × 2 framework of octahedral manganese oxo units based on the cryptomelane-type framework. Herein, we describe a niobium (Nb) substituted mixed metal oxide of Nb and Mn where the cryptomelane-type framework is retained. These materials are hydrothermally synthesized from the reaction of potassium permanganate, manganese sulfate, and homogeneous niobium(v ) precursors. Niobium incorporation up to 31 mol% can be achieved without destroying the one dimensional 2 × 2 framework. The yields of the materials vary between 70 and 90%. These materials are analyzed by powder XRD, BET isotherm, TEM, SEM, XRF, and XPS studies. The synthesized materials show promising activity in selective oxidation of methanol to dimethoxymethane (DMM) at 200 °C. Normalized activity correlations followed the trend 21% Nb-OMS-2 > 15% Nb-OMS-2 > 31% Nb-OMS-2 > 68% Nb-OMS-2 > K-OMS-2. A fluctuation in methanol conversion was observed around 125–150 °C in most samples, suggesting this to be a catalytically important temperature regime when forming active sites for DMM production.