A Lamellar MWW Zeolite With Silicon and Niobium Oxide Pillars: A Catalyst for the Oxidation of Volatile Organic Compounds

Abstract

In this work, an MWW‐type zeolite with pillars containing silicon and niobium oxide was synthesized to obtain a hierarchical zeolite. The effect of niobium insertion in the pillaring process was determined by combining a controllable acidity and accessibility in the final material. All pillared materials had niobium occupying framework positions in pillars and extra‐framework positions. The pillared material, Pil‐Nb‐4.5 with 4.5 wt % niobium, did not compromise the mesoporosity formed by pillaring, while the increase of niobium in the structure gradually decreased the mesoporosity and ordering of lamellar stacking. The morphology of the pillared zeolites and the niobium content were found to directly affect the catalytic activity. Specifically, we report on the activity of the MWW‐type zeolites with niobium catalyzing the gas‐phase oxidation of volatile organic compounds (VOCs), which is an important reaction for clean environmental. All produced MWW‐type zeolites with niobium were catalytically active, even at low temperatures and low niobium loading, and provided excellent conversion efficiencies.

Structure and reactive properties of Nb-impregnated two-dimensional pillared MWW zeolites for total oxidation of volatile organic compounds

“…Regarding the Nb concentration on pillared zeolites, Nb0.1/HMCM-36 showed 92% conversion of benzene, which was 7% higher than with Nb0.05/HMCM-36 and indicates that the increase of Nb content in the pillared material influences the catalytic activity. The catalytic performance of Nb0.1/HMCM-36 was even superior to the pillared MWW zeolites obtained by insertion of the Nb source (Nb ethoxide) in the pillaring step [17]; the synthesized material with higher Nb content (14.8%) presented benzene, toluene and o-xylene conversions of 86%, 66% and 34%, respectively, and reveals that the methodology of Nb incorporation in MCM-36 influences the oxidation of BTX. The superior performance of Nb0.1/HMCM-36 suggests that the impregnation method allows Nb species to be obtained in a homogeneous distribution on the surface of the pillared zeolite, while the insertion of Nb during the pillaring step could lead to some occluded species inside the pillar walls that are not accessible to the reactants.…”

“…Examples include the use of alkoxide mixtures including TEOS and tetrabutyl orthotitanate (TBOT) to obtain Si/Ti-pillared MCM-36 for epoxidation [14], TBOT to obtain pure Ti-pillared MCM-36 for the CO2 capture [15] and a mixture of TEOS and niobium (Nb) ethoxide to obtain MCM-36 with pillars of niobiosilicate for liquid-phase oxidation of cyclohexene and methylene blue [16]. Recently, our group reported MCM-36 with Si/Nb oxide pillars using TEOS and Nb ethoxide, applied for the gas-phase total oxidation of volatile organic compounds (VOC), including BTX (benzene, toluene and xylene) [17].…”

Modifying Y zeolite with chloropropyl for improving Cu load on Y zeolite as a super Cu/Y catalyst for toluene oxidation

“…Their activity is noticeably higher compared to other catalysts reported in the literature (Table S4 †), such as Co-, Mn-and Nb-containing zeolites (BEA and clinoptilolite and MWW) under the same experimental conditions, which gave the similar conversion of toluene at much higher temperatures (T 90 > 320 C). 10,22,58,59 In addition, NaY zeolite as support presents high stability without noticeable deactivation in the oxidation reaction, while CuKIL samples show 9-23% toluene conversion loss in the initial 75 min of reaction. 55 Therefore, Cu-based NaY catalysts modi-ed by other organic groups deserve careful research for VOCs catalytic oxidation.…”

Synthesis and Crystal Structure of a New RTH‐Type Precursor and Its Interlayer Expanded Zeolite

“…The direct prepared 2D zeolites or post-modified derivatives have performed excellent acidity catalytic properties in various areas, like petrochemistry, oxidation reactions, fine chemical synthesis, and organometallics, thus drawing a growing and permanent attention. [17] To meet the demand for the diversity of zeolites applied in various catalysis fields, preparation of 2D zeolites with different structural and chemical modifications is still a challenge.…”