Citronellal cyclisation to isopulegol over micro-mesoporous zsm-5 zeolite: effects of desilication temperature on textural and catalytic properties

Methods for Preparing Hierarchical Zeolites by Chemical Etching and Their Catalytic Applications: A Review

“…Shah et al have demonstrated desilication of ZSM-5 by employing a mixture of NaOH and CTAB, thus yielding micro-mesoporous zeolites with superior properties. [21] The addition of CTAB to the microporous ZSM-5 served to significantly increase the surface area, leading to the synthesis of micro-mesoporous zeolites with improved physicochemical and catalytic properties. During the desilication process, the reaction between NaOH and the zeolite structure resulted in the removal of a specific amount of Si atoms, causing a decrease in the Si/Al ratio.…”

Enantiomeric Isopulegol as the Chiral Pool in the Total Synthesis of Bioactive Agents

“…A wide range of Lewis acid and Brønsted catalysts such as InCl 3 , [19] ZnBr 2 , [20] ZnBr 2 /SiO 2 , [21] ZnCl 2 /SiO 2 , [22] Al 2 O 3 / SiO 2 , [23] ZnBr 2 /C 8 -HMS, [24] Zr-beta-100, [25] SÀ ZrO 2 -CMS (carbon molecular sieve), [26] ZrO 2 À 16-PO 4 -500, [27] Zr-TUD-1, [28] H-MCM-41, [15] Al/Fe-pillared Clay (Al/Fe/PILC), [29] BINOLÀ Al, [30] H 3 PW 12 O 40 /SiO 2 , [13] HfO 2 (SiO 2 ) 8 , [31] TBA 3 H-[γ-SiW 10 O 36 {Al(OH 2 )} 2 (μ-OH) 2 ].4H 2 O, [32] WO 3 /SiO 2 /Al 2 O 3 (W25 IMP), [33] HS-AlF 3 , [34] NbÀ AlF 3 À OH, [35] Eco-Mn 1 , [36] zeolite (H-BEA), [37] zeolite (ZSM-5) [38] was developed to improve selectivity for formation of (À )-isopulegol in the cyclisation of (+)-citronellal. The Table 1 summarised the results.…”

Design of Nickel Supported Hierarchical ZSM-5/USY Zeolite Bifunctional Catalysts for One-Pot Menthol Synthesis via Liquid-Phase Citral Hydrogenation

“…Among them, citral—or 3,7-dimethyl-2,6-octadienal—is known as an utmost versatile compound for the production of nerol, geraniol, isopulegol, menthol, citronellal, and dihydrocitronellal via consecutive hydrogenation and cyclisation catalytic reactions [ 4 ]. Likewise, in a catalytic citral hydrogenation reaction, the most important task is to produce menthol via one-pot synthesis from liquid-phase citral hydrogenation with the help of consecutive catalytic reactions, such as (i) citral hydrogenation to citronellal, (ii) citronellal cyclisation to isopulegol, and (iii) isopulegol hydrogenation to menthol [ 5 , 6 ], as shown in Scheme 1 . The increasing world demand and price volatility of natural menthol have led to research on the possible synthesis of menthol from other raw materials.…”

“…Various catalytic-material-supported (metals), such as H-MCM-41, Al-MCM-41, H-Y zeolite, beta zeolite, activated carbon, Zr-zeolites, ionic liquid catalysts, nickel-supported metals [ 9 ], MOF-derived AgCo alloy nanoparticles [ 10 ], Pt/Sn [ 11 ], Ru-HY extrudates [ 12 ], Pt/SiO 2 [ 13 ] nano-composite catalysts [ 14 ], ruthenium nanoparticles [ 15 ], and SiO 2 -Al 2 O 3 , have been applied in citral hydrogenation reactions to obtain a higher yield of menthol [ 16 , 17 ]. Conversely, it has been observed that menthol selectivity would possibly be decreased due to the lack of active and selective catalyst designs that occur because of the formation of undesired/unrestrained hydrogenations, as well as cracking side reactions [ 5 , 6 ].…”

“…Among the innumerable superior catalytic materials, zeolite-based materials (e.g., Na-ZSM-5 and Na-Y) have been widely used for chemical organic reactions (e.g., hydrogenation, cracking, dehydration, and isomerization) [ 18 ]. However, previous literature reviews have highlighted the limitations of zeolite-based materials for bulky molecules/chemical reactants due to the narrow pore size of zeolite materials [ 5 ]. Additionally, the narrow pore size textural characteristics would also obstruct mass transfer, as well as the diffusion of reactant molecules, which would lead to the declination of catalytic reaction performance and product selectivity.…”