Conversion of Ethene to Propene on Nickel Ion-loaded Mesoporous Silica Prepared by the Template Ion Exchange Method

Abstract

Although surface of amorphous silica is widely accepted to be neutral or slightly acidic, siliceous mesoporous materials have been found to act as excellent acid catalysts by us and other groups. On the other hand the increment in propene production is one of the significant objectives to be achieved in the present petroleum chemistry. Especially the one-path conversion of ethene to propene (ETP reaction, 3C 2 H 4 ? 2C 3 H 6 ) is the most desired process. In our efforts, the specific acid catalysis of mesoporous silica was combined with the catalysis of nickel ion, which could turn the new type of ETP reaction into reality. The one-path conversion of ethene was 68% and the propene selectivity was 48% with 43% of butenes in a continuous gas-flow system at 673 K and an atmospheric pressure. The reactivity of lower olefins and the dependences of the ETP reaction on the contact time and the partial pressure of ethene followed the reaction mechanism consisting of dimerization of ethene to 1-butene, isomerization of 1-butene to 2-, and metathesis of 2-butene and ETP. The Ni-loaded mesoporous silica catalysts were characterized mainly by EXAFS and TPR techniques. The local structures of the nickel species active for the ETP reaction were very similar to that of layered nickel silicate, while those on the inert catalysts were the same as that of NiO particles.

Ethanol Conversion on MCM-41 and FSM-16, and on Ni-Doped MCM-41 and FSM-16 Prepared without Hydrothermal Conditions

“…The Ni-doped catalyst prepared from FSM-16 showed greater activity than that prepared from MCM-41. Iwamoto et al [1,3] reported that Ni-MCM-41 has the unique ability to catalyze the direct formation of propylene from ethylene, which is selectively obtained via dehydration of ethanol on the MCM-41 prepared in their laboratory [4,16]. Therefore, the results shown in Figs Fig.…”

“…A recent report suggests that propylene can be directly obtained from ethylene on MCM-41 (#41 of Mobile Composition of Matter) doped with nickel cations (Ni-MCM-41) [1]. It is generally known that propylene, ethylene, and other petroleum-related compounds are commonly produced by thermal cracking of naphtha.…”

“…Based on this background information, we investigated, and then confirmed, the direct conversion of ethanol to propylene on Ni-doped MCM-41. Based on the mechanism for the conversion of ethylene to propylene [1], the direct conversion of ethanol to propylene on Ni-MCM-41 proceeds via the following series of reaction: dehydration of ethanol to ethylene on an acidic site (Eq. 1); dimerization of ethylene to 1-butene on the Ni-site (Eq.…”

Ordered Mesoporous Aluminosilicates Assembled from Dissolved LTA Precursors

“…In catalysis, mesoporous materials supported metal and metal oxide nanoparticles have received extensive attention [21][22][23][24]. Iwamoto and Kosugi [23] and Iwamoto [24] reported that the ethane-topropene reaction could be catalyzed on nickel ion-loaded mesoporous silica catalysts. The acidity of 1.4-MS and by limitations on the diffusion of reactants and the intermediate products.…”

Theoretical identification of structural heterogeneities of divalent nickel active sites in NiMCM-41 nanoporous catalysts

“…The nickel ions incorporated into the ordered mesoporous materials (OMMs) have also been suggested as efficient catalysts for the gas-phase transformation of ethylene to propylene [25][26][27][28][29][30][31][32][33][34]. For instance, the performance and durability of Ni/MCM-41 catalysts prepared from a nickel citrate precursor was ranked as auspicious with a promising potential for closing the gap between the propylene demand and supply [35].…”