Ga-MCM-41 synthesis and catalytic activity in the liquid-phase isomerisation of α-pinene

Isomerization of α-Pinene to Monocyclic Monoterpenes in Hot Compressed Water Using TiO2 and WOx/TiO2 Catalysts

“…Based on the experimental data and previous reports, ,,,, a lumped reaction scheme for kinetic analysis was proposed (Figure ). In acid-catalyzed reactions, the carbon double bond in α-pinene is first protonated and a pinanyl cation is produced.…”

“…The acid-catalyzed isomerization of α-pinene has also been widely researched, and the reaction catalyzed by solid acids has attracted particular attention. The acid-catalyzed isomerization of α-pinene has been reported to produce monocyclic, bicyclic, and tricyclic monoterpenes such as camphene, β-pinene, bornylene, α-fenchene, tricyclene, limonene, terpinolene, α-terpinene, γ-terpinene, and isoterpinolene. − One of the most important of these products is camphene, and a number of researchers have investigated its selective production. For example, Simakova et al reported that the selectivity for camphene reaches 60–80% at a 99.9% conversion of α-pinene when using a Au/γ-Al 2 O 3 catalyst .…”

“…For example, Simakova et al reported that the selectivity for camphene reaches 60–80% at a 99.9% conversion of α-pinene when using a Au/γ-Al 2 O 3 catalyst . With regards to product selectivity, it has been reported that bicyclic monoterpenes (such as camphene) are preferentially formed on Lewis acid sites while monocyclic monoterpenes (such as limonene) are preferentially formed on Brönsted acid sites. ,, In the presence of both solid-acid catalysts and water, the hydration of monoterpenes occurs, and alcohols such as α-terpineol, 4-terpineol, and 1,8-terpene are produced in addition to monoterpenes. − Mochida et al examined the hydration of α-pinene over zeolite catalysts with different SiO 2 /Al 2 O 3 ratios and reported that more hydrophobic zeolites show higher activity because only a small number of water molecules competitively adsorb on the acid sites.…”

Highly-selective solvent-free catalytic isomerization of α-pinene to camphene over reusable titanate nanotubes

“…This phenomenon is good agreement with results previously published. 27 The effects of reaction time on the isomerization were investigated, and results are presented in Fig. 7.…”

The Synergistic Effect of Bimetallic Zn–Ti in MCM-41 Support for the Improvement of Catalytic Activity

“…[3][4][5] However, the lack of necessary active sites of pure silica M41S materials may limit their usages as catalysts. 6 Therefore, numerous investigations have been focused on the incorporation of transition metal ions like Mn, 7 Fe, 8 V, 9 Ni 10 and Ti 11 and some main group elements like B, 12 Al 13 14 and Ga 15 into the materials to generate active sites in order to improve the catalytic activity. In principle, bimetal incorporation is able to modify the surface properties of mesoporous silicate more effectively than single metal in the catalysis field, which is getting attraction among researchers recently.…”