Role of Recrystallization in Alkaline Treatment on the Catalytic Activity of 1‐Butene Epoxidation

Abstract

Two alkylol amines, which were ethanolamine (EOA) and triethanolamine (TEOA), were used to posttreat nanosized titanium silicalite‐1 (TS‐1) to improve its catalytic activity for 1‐butene epoxidation. Comparative studies were conducted to clarify the influences of the EOA and TEOA concentrations on the physicochemical properties through detailed characterization. EOA treatment can dissolve the framework Si, [SiO4], on the external surface of TS‐1, generating some macropores. TEOA serves as structure‐directing agent to form MFI topology other than the dissolution of [SiO4], and promotes the recrystallization of [SiO4], forming new TS‐1 particles over the external surface. The two treatments can both improve the catalytic activity of 1‐butene epoxidation, but the samples treated with TEOA exhibit better catalytic stability. This can be attributed to the characteristic recrystallization of [SiO4] in the case of TEOA treatment, stabilizing the structure of TS‐1 and maintaining more framework Ti and intercrystal space.

Heteroatom zeolites with a high content of framework metal sites as Lewis-acid catalysts for the conversion of ethanol–acetaldehyde to 1,3-butadiene

“…The conversion, selectivity, and space time yield were calculated through the formula below. 27,37,39,40 Conversion % Moreover, the sample failed to crystalize via direct synthesis due to the high content of heteroatoms, even up to 20 days, in line with the conclusion reported in the literature that high content metals inhibit nucleation. 13,41,42 The XRD patterns (Fig.…”

“…The conversion, selectivity, and space time yield were calculated through the formula below. 27,37,39,40 Space time yield (g g cat −1 h −1 ) = conversion × selectivity × WHSV…”

“…Dissolution-reconstruction (DRC) is an effective approach for the development of mesoporosity in zeolites, where recrystallization after the dissolution of the zeolite framework is favorable for maintaining the framework of metals. 37 Inspired by this idea, an improved dissolution-reconstruction (IDRC) strategy is proposed for achieving a high content of framework metal sites in heteroatom zeolites. Apart from the dissolution-reconstruction strategy of the parent *BEA framework, the better dispersion of Zr species via controllable dissolution and hydrolysis of the Zr precursor are the key improvements in IDRC, which guarantees strong interactions between the hydrolyzed Zr and Si species and thus more isolated tetrahedral Zr incorporation.…”

Molecular Structure Effect on the Epoxidation of 1-Butene and Isobutene on the Titanium Silicate Catalyst under Transient Conditions in a Trickle Bed Reactor

“…Direct epoxidation of propene to propene oxide has achieved successful industrial implementations under mild reaction conditions . However, even if ethene − and 1-butene − epoxidation has attended recent research interest, most of the previous research has aimed to compare different catalysts more than to investigate how the epoxidation reaction and side reactions are affected by the different process parameters. The studies have in most cases been limited to the use of batch reactor technology or fixed beds operating under stationary conditions.…”

“…The available literature reports studies on catalyst modifications, − solvent effects, , and reactor − configurations for propene epoxidation, while for butenes, most of the previous investigations have been devoted to catalyst modifications applied in batch reactors without any detailed studies on the product selectivity and reactant conversion. − Nevertheless, the studies carried out in continuous mode for 1-butene epoxidation are reported over 10 h of reaction displaying a constant decrease in the catalyst activity with time-on-stream in each catalyst tested, evidently due to the reactant and product capture on the catalyst surface. , Therefore, it is important to study these two reaction systems in a broad set of conditions to understand if isomers have similar reaction mechanisms and catalyst activities. On the other hand, it is necessary to work in a continuous regime due to the changes reported for 1-butene between 10 and 350 h. , Isobutene epoxidation has not been reported extensively; the study of the epoxidation of isobutene has been reported once to compare the rate with other olefins without any deeper analysis of the byproducts.…”