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A very green catalytic method has been introduced for the synthesis of alkylaromatic ketones by solvent-free benzylic oxidation of alkylaromatics with molecular oxygen (O2) over hexagonally mesostructured MnSBA-15 catalysts synthesized with a variety of manganese (Mn) contents using a pH-adjusting direct hydrothermal (pH-aDH) method. For example, the solvent-free oxidation of ethylbenzene (EB) over different mesoporous MnSBA-15 catalysts and uniform pore sized MnMCM-41(31) prepared by an alkaline hydrothermal method has been systematically evaluated. Washed MnSBA-15(4) (W-MnSBA-15(4)) or green mesoporous MnSBA-15(4) obtained after the removal of the non-framework octahedral Mn2O3 species deposited on the active surface of MnSBA-15(4) using a promising chemical treatment method is used for this reaction to evaluate its catalytic activity. Meanwhile the recyclability and hot-filtration experiments for this reaction have been also studied. The catalytic activities obtained from the above catalytic results prove that the W-MnSBA-15(4) has higher EB conversion and AP[double bond, length as m-dash]O selectivity than the other mesoporous catalysts used in this reaction. Therefore, in order to find the optimal reaction parameters for this reaction, various reaction parameters with W-MnSBA-15(4) have been thoroughly evaluated. Using W-MnSBA-15(4), the catalytic results obtained with different oxidants used in this reaction have also been discussed clearly. The catalytic results of solvent-free benzylic oxidations with W-MnSBA-15(4) conducted with different alkylaromatic molecules have been obviously discussed. All the mesoporous catalysts used in this reaction have been characterized using several instrumental techniques to confirm them as the standard mesoporous catalysts. The plausible reaction mechanism for the solvent-free oxidation of EB has been successfully reported based on the characterization results of the catalyst and catalytic results. The ESR and UV-vis DRS results of the W-MnSBA-15 catalyst used in these reactions corroborate that the disordered octahedral divalent (Mn2+) and tetrahedral trivalent (Mn3+)-species have been successfully incorporated on the silica surface of the catalysts. Based on the catalytic results, it is noteworthy to observe that mesoporous W-MnSBA-15(4) is a highly active, green and promising heterogeneous catalyst for the selective synthesis of alkylaromatic ketones, since the catalyst produces the best catalytic activity among the other mesoporous Mn silicate catalysts.

A robust, magnetically recoverable Fe3O4@SiO2-SO3H core@shell nanoparticulate acid catalyst was successfully synthesized by a stepwise co-precipitation, coating, and functionalization. It was utilized as a heterogeneous catalyst for the transesterification and esterification of triglycerides and free fatty acids in Jatropha curcas oil (JCO) to a fatty acid methyl ester (FAME) mixture. This product conformed to ASTM standards for biodiesel. The as-prepared catalyst had a magnetic saturation of 30.94 emu g−1, surface area of 32.88 m2g−1, acidity of 0.76 mmol g−1, and pore diameter of 3.48 nm. The catalyst showed 98 ± 1% conversion using the optimized reaction conditions of methanol:oil molar ratio of 9:1, 8 wt% catalyst loading, 80 °C, and 3.5 h. The transesterification of JCO to FAME using the present catalyst benefitted from a very low activation energy of 37.0 kJ mol−1. The solid acid catalyst exhibited excellent chemical and thermal stability, and also reusability based on easy separation from the reaction mixture due to its inherently magnetic nature. Modest deterioration in oil conversion after multiple uses was offset by one-pot, quantitative regeneration of catalyst active sites. This enabled identical performance in JCO methyl transesterification and esterification in the 1st and 10th catalytic cycles.

We demonstrate a very eco-friendly and single-step catalytic method for the highly selective synthesis of 1,2,3,4,5,6,7,8-octahydroacridine (OHA) by the vapour phase aminocyclization of cyclohexanone (CyO) with a mixture of formaldehyde (HCHO) and ammonia (NH3) over mesoporous bimetallic ZnAlMCM-41 (ZnAl-41) molecular sieves as efficient catalysts, which were synthesised by a simple basic hydrothermal method. To find optimum parameters for the synthesis of OHA, different reaction parameters, such as temperature, time on stream (TOS), weight hourly space velocity (WHSV), and feed molar ratios of CyO : HCHO : NH3, have been extensively studied. The used ZnAl-41 catalysts were treated by washing and calcination to recover the recyclable catalysts which were then reused in these reactions to study their catalytic abilities. To selectively synthesize a variety of pyridine compounds, the active mesoporous catalysts, namely, ZnAl-41(75) and recyclable ZnAl-41(75), with different reaction parameters, were extensively used in the vapour phase aminocyclization reaction with different aldehydes and cycloketones, and produced excellent product selectivities, e.g., 9-alkyl substituted octahydroacridines (9-ASOHAs) and diannelated pyridines (DAPs), with good ketone conversions. In this catalytic reaction, OHA, 9-ASOHAs and DAPs are the main products and are important as starting materials in the preparation of biologically active compounds, drugs, dyes and alkaloids. It is shown by our remarkable catalytic results that the ZnAl-41(75) catalyst, as an environmentally friendly heterogeneous catalyst, has outstanding catalytic activity in the production of OHA, 9-ASOHAs and DAPs by a single-step synthetic method.

The major product, 2,3,5-trimethyl-1,4-benzophenone (TMB[double bond, length as m-dash]O), was synthesised by an eco-friendly liquid-phase oxidation of 2,3,6-trimethylphenol (TMP-OH) over Cu(ii)-containing propylsalicylaldimine (CSA) functionalized mesoporous solid catalysts, namely, CSASBA-15(0.2), CSASBA-15(0.1) and CSAMCM-41(0.2), synthesized using various amounts of copper in a simple post-grafting method using different mesoporous silica materials, e.g., thick-silica walled SBA-15 and thin-silica walled MCM-41. The benzoquinones, i.e., 2,6-disubstituted p-benzoquinones (DSBQs), were also synthesised by the slurry-phase oxidation of di/tri-substituted phenols using the prepared catalysts. A promising chemical treatment was used for the removal of extra-framework copper species from the active surface of CSASBA-15(0.2), and the catalytic activity of the recovered catalyst, i.e. green mesoporous CSASBA-15(0.2) or W-CSASBA-15(0.2), was evaluated. Various reaction parameters, oxidants and solvents were used in this catalytic oxidation. To confirm the catalytic stability, recyclability and hot-catalytic filtration experiments were performed. On the basis of all catalytic results, it is worth noting that the mesoporous CSASBA-15(0.2) is an outstanding and a promising heterogeneous catalyst for the selective synthesis of TMB[double bond, length as m-dash]O and DSBQs, and produces 98% TMB[double bond, length as m-dash]O selectivity with 100% TMP-OH conversion at 353 K for 40 min and 97-99% DSBQ selectivity with 98-100% di/tri-substituted phenols conversion at 330 K for 1-3 h. The green mesoporous catalyst has unprecedented catalytic activity compared with that of other CSA functionalized mesoporous solid catalysts.

Ionic liquids immobilized onto structurally modified polyethylene glycol (PEG) were prepared through the reaction of 1-(2-hydroxyl-ethyl)-3-alkyl-imidazolum chloride and PEG-succinic acid. Elemental analysis, SEM, 13 C NMR and FT-IR showed that the immobilized ionic liquid groups were well incorporated onto the PEG support. The PEG-supported ionic liquids (PEG-IL) proved to be an effective heterogeneous catalyst for the solventless synthesis of cyclic carbonate from allyl glycidyl ether (AGE) and carbon dioxide. PEG of lower molecular weight had higher conversion of AGE. High temperature and carbon dioxide pressure and the presence of zinc halide co-catalyst were favorable for AGE conversion. PEG-IL can be reused for the reaction through up to three consecutive runs without significant loss of its catalytic activity.

Mesoporous CrSBA-15 catalysts synthesized with a variety of n Si / n Cr ratios by pH-aDH method were used in the production of enones by the liquid-phase oxidation of benzylic compounds. To investigate the leaching of chromium species on the silica surface, CrSBA-15(8) was chemically treated with ammonium acetate solution while the Cr-containing mesoporous silica catalysts used for these reactions were regenerated by washing and calcinations. The treated catalysts such as washed CrSBA-15 and regenerated CrSBA-15 catalyst were used/reused in these reactions to find their catalytic activities. Furthermore, the influences of various reaction parameters such as temperature, time, ratios of reactant and solvents on the synthesis of tetraline (T O) have been systematically investigated. Based on the catalytic investigations, CrSBA-15(8) catalyst is found to be a highly active, recyclable and promising heterogeneous catalyst for the selective synthesis of enones, and it has superior catalytic activity in the oxidation of benzylic compounds than CrMCM-41.

Mesoporous CeSBA-15 catalysts with a variety of n Si / n Ce ratios have been synthesized under pH-adjusting direct hydrothermal (pH-aDH) method using cerium (IV) sulphate tetrahydrate and Pluronic P123 as the sources of cerium and template, respectively. For comparison studies, Ce/SBA-15(10) catalyst has been synthesized by an incipient wetness impregnation (IWI) method. The hydrothermal stabilities of CeSBA-15 catalysts have been investigated in boiling water (373 K) at autogenous pressure for 168 h. The mesoporous CeSBA-15 catalysts synthesized by different methods have been characterized using the relevant techniques viz. ICP-AES, XRD, N 2 adsorption, UV–vis DRS, EPR, 29 Si MAS NMR, TEM and FE-SEM, and their characteristic results show that the CeSBA-15 catalysts synthesized by pH-aDH method have higher tetrahedral cerium-ions with two-dimensional mesostructures than the Ce/SBA-15(10) synthesized by IWI method. In addition, CeSBA-15(10) has higher hydrothermal stability than CeSBA-15(50). The CeSBA-15 catalysts have been tested in the liquid phase oxidation of cyclohexane with hydrogen peroxide (H 2 O 2 ). Based on the catalytic activities of all catalysts, CeSBA-15(10) is found to be a highly active, recycle and promising heterogeneous catalyst for the oxidation of cyclohexane.

Two-dimensional mesoporous SBA-15 catalysts synthesized by different hydrothermal methods have been used, for the first time, in the liquid-phase oxidation of α-pinene with t -butyl hydrogen peroxide (TBHP) for the synthesis of verbenone (V O). The recyclable CrSBA-15 catalysts have also been reused in this reaction to find their catalytic activities. To investigate the leaching of chromium species on the silica surface, CrSBA-15(8) has been treated with ammonium acetate solution, and it has been also treated with boiling water for the investigation of hydrothermal stability. The treated CrSBA-15(8) catalyst has been used in the catalytic reaction for finding the effects of catalytic stability. The influences of various reaction parameters such as temperature, time, ratios of reactant (α-pinene-to-TBHP) have been extensively investigated for the synthesis of V O. In addition, the liquid-phase oxidation of α-pinene has been conducted with different solvents to find the best solvent with a good catalytic activity. On the basis of all investigations with a hypothetical reaction pathway of α-pinene oxidation, the CrSBA-15(8) catalyst is found to be a highly active, recyclable and promising heterogeneous catalyst in the liquid-phase oxidation of α-pinene for highly selective synthesis of V O. Furthermore, CrSBA-15(8) catalyst has higher selectivity of V O (88.2%) than other CrSBA-15 and CrMCM-41.

Mesoporous TiSBA-15 catalysts have been synthesized using Pluronic P123 as a structuring agent under pH-adjusting direct hydrothermal (pH-aDH) method. The mesoporous TiSBA-15 catalysts characterized by sophisticated instrumental techniques via. ICP-AES, XRD, N 2 adsorption, FE-SEM, TEM, UV–vis DRS and 29 Si MAS NMR show their two-dimensional mesostructures with tetrahedral titanium on the silica surface. The highly ordered TiSBA-15 catalysts have been used in the liquid-phase oxidation of 2-methyl-1-naphthol (2M1N-OH) with hydrogen peroxide (H 2 O 2 , 30%), for the synthesis of vitamin K 3 (2-methyl-1,4-naphthoquinone). The recyclable TiSBA-15 catalysts have also been reused to find their catalytic activities. The influences of various reaction parameters such as temperature, time, ratios of reactant (2M1N-OH: H 2 O 2 ) have been then investigated in this catalytic reaction for the highly selective synthesis of vitamin K 3 . In addition, the liquid-phase oxidation of 2M1N-OH has been carried out with different solvents to find the best solvent with a good catalytic activity. Based on the all catalytic studies, TiSBA-15(6) catalyst is found to be a highly active and eco-friendly heterogeneous catalyst for the selective synthesis of vitamin K 3 . Furthermore, TiSBA-15(6) catalyst has higher 2M1N-OH conversion (100%) and vitamin K 3 selectivity (93.2%) than other TiSBA-15 and TiMCM-41(40).

A novel CSA-SBA-15 has been synthesized under mild reaction condition using mesoporous SBA-15 synthesized by pH-adjusting method with organic modifying reagents and copper nitrate trihydrate, and it has been characterized by XRD, FTIR, N 2 adsorption, ESR, UV–vis DRS, FE-SEM and TEM for the investigation of nature of copper species and its interaction with SA-SBA-15. The results of elemental analysis obtained by CHN and ICP-AES show that the molar ratio of N:Cu is ≈3.5, and the molar ratio of C:Cu is ≈23.8. ICP-AES result shows the number of copper-ions (ca. 0.198 wt.%) coordinated with SA-SBA-15. The FTIR results confirm the amine and azomethine groups grafted on SBA-15 while the results of ESR and UV–vis DRS confirm the Cu(II) species anchored on SA-SBA-15. The CSA-SBA-15 is found to be a highly active and recycle heterogeneous catalyst for the selective syntheses of olefin epoxides, and it has superior catalytic activity in the epoxidation of olefins than metal ions incorporated/impregnated mesoporous catalysts.

Highly ordered two-dimensional SnSBA-15 molecular sieve catalysts with different concentrations of tin species have been synthesized using Pluronic P123 as a structure directing agent under pH-adjusting direct hydrothermal method and have been used for synthesis of nopol by Prins condensation of β-pinene with paraformaldehyde. The influence of various reaction parameters on this reaction has been investigated. The Prins condensation reaction has also been carried out with different solvents for finding the best solvent with a good catalytic activity. In addition, the Prins condensation of β-pinene with paraformaldehyde in the presence of propyl cyanide with water has been carried out for the synthesis of nopol, and in this condition the catalytic activity of the catalyst used was not seriously affected. On the basis of all catalytic results, SnSBA-15(5) is found to be a highly active, water-resistant and recyclable heterogeneous catalyst for selective synthesis of nopol.

The synthesis of Fe-SBA-16 with isolated framework Fe species was achieved by simple adjustment of molar ratio of co-surfactant n-butanol, TEOS, n H 2 O / n HCl ratio, Si/Fe ratio, and aging condition, respectively. The extent of mesopore structural ordering and the coordination of iron are confirmed by X-ray diffraction, N2 physisorption, 29Si-MAS NMR, SEM, TEM, electron spin resonance (ESR), and NH3-TPD analysis. The material obtained constitutes micro- (∼316 m2/g) and mesopore surface area (∼1000 m2/g), with high-mesopore sizes (∼9.8 nm). The micropore volume present up to 0.28 cm3/g, while the total pore volume range ∼0.90 cm3/g at the maximum. Among various Si/Fe ratios synthesized, Fe-SBA-16 with Si/Fe ratio 19 exhibited good catalytic activity for the oxidation of cyclohexene at the optimized reaction condition.

Epoxidation of styrene with t -butyl hydroperoxide (TBHP) as an oxidizing agent has been conducted under liquid phase reaction conditions over Zr–Mn-MCM-41 with different n Si /( n Zr + n Mn ) ratios and Mn-MCM-41(31) catalysts for selective synthesis of styrene oxide. The influences of various reaction parameters such as temperature, time, oxidants, and solvents, styrene to TBHP mmol ratios and acetonitrile (MeCN) to N , N -dimethylformamide (DMF) volume ratios on the conversion of styrene and the selectivity of styrene oxide have also been studied. With the decrease of the n Si /( n Zr + n Mn ) ratios of Zr–Mn-MCM-41 catalysts from 327 to 49, the conversion of styrene as well as the yield and selectivity of styrene oxide increase due to the increase of the number of Lewis acid sites on the surface of catalysts. Moreover, the conversion and selectivity in Zr–Mn-MCM-41(49) is higher as compared to that of Mn-MCM-41(31). The Zr–Mn-MCM-41(49) is found to be reusable for the epoxidation of styrene with TBHP for selective synthesis of styrene oxide.

Isopropylation of m-cresol with isopropyl alcohol (IA) as an alkylating agent has been conducted under vapor phase reaction conditions over mesoporous Zn–Al–MCM-41 catalysts with different nSi/(nZn + nAl) ratios for highly selective synthesis of thymol. The influence of reaction parameters such as reaction temperature, WHSV, mole ratio of reactants, time-on-stream and recyclability reactions, have also been investigated. With increasing the nSi/(nZn + nAl) ratios of Zn–Al–MCM-41 catalysts from 75 to 380, conversion of m-cresol and yield as well as selectivity of thymol decrease because the number of Bronsted acid sites in Zn–Al–MCM-41 catalysts are found to decrease almost linearly with increasing ratios of nSi/(nZn + nAl) from 75 to 380. The conversion of m-cresol and selectivity of thymol in Zn–Al–MCM-41(75) remain constant with each cycling of reaction because of no loss of catalytic activity on the inner side surface of pore walls. Furthermore, these catalytic results are compared with those obtained by using Al–MCM-41(with different nSi/nAl ratio = 21, 42 and 104), HY, Hβ, HM and H-ZSM-5 zeolites. Based on the comparison of catalytic results, Zn–Al–MCM-41(75) is found to be a highly active and recyclable heterogeneous catalyst for the highly selective synthesis of thymol.

Mesoporous GaSBA-15 molecular sieves with different n Si /n Ga ratios have been directly synthesized using Pluronic 123 triblock polymer as a structure-directing agent by pH-adjusting method. The mesoporous materials have been characterized using ICP-AES, XRD, N 2 adsorption, 71 Ga-MAS NMR, SEM and TEM. ICP-AES studies show a high amount of gallium incorporation on the silica pore walls. The structural and textural properties of calcined GaSBA-15 are characterized by XRD and N 2 adsorption. 71 Ga MAS NMR results demonstrate that a high amount of tetrahedral-gallium could be substituted for Si in the framework of SBA-15. TEM and FE-SEM images show the uniform pore diameter and rope-like hexagonal mesoporous structure of GaSBA-15. These GaSBA-15 materials have been used as catalysts for vapour-phase t-butylation of 1,2-dihydroxybenzene (DHB) for selective synthesis of 4-t-butylcatechol (4-TBC) under different reaction conditions. GaSBA-15(10) gave the highest 93.2% conversion of DHB and 95.7% selectivity of 4-TBC as compared with other GaSBA-15 catalysts.

Mesoporous CrSBA-15 molecular sieves with different n Si / n Cr ratios have been directly synthesized, for the first time, using Pluronic 123 triblock polymer [(EO) 20 (PO) 70 (EO) 20 ] as a structure-directing agent by NH 4 F acidic method and pH-adjusting method. The mesoporous materials have been characterized using ICP-AES, XRD, N 2 adsorption, ESR, SEM and TEM. ICP-AES studies show a higher amount of chromium incorporation on the silica pore walls in pH-adjusting method as compared to NH 4 F acidic method; however, more octahedral Cr 3+ species are oxidised using pH-adjusting method than those using NH 4 F acidic method. The structural and textural properties of calcined CrSBA-15 are characterized by XRD and N 2 adsorption. ESR results show that both octahedral Cr 3+ and tetrahedral Cr 5+ /Cr 6+ are coordinated on the silica surface of calcined CrSBA-15 prepared using NH 4 F acidic method whereas only tetrahedral Cr 5+ /Cr 6+ are coordinated on the silica surface of calcined CrSBA-15 prepared using pH-adjusting method. TEM and FE-SEM images show the uniform pore diameter and rope-like hexagonal mesoporous structure of CrSBA-15. CrSBA-15 materials have then been used as catalysts for liquid-phase oxidation of anthracene for selective synthesis of 9,10-anthraquinone under different optimal conditions using benzene as the solvent and t -BHP as the oxidant. CrSBA-15(4) gave the highest conversion of 90.6% of anthracene and 100% selectivity of anthraquinone as compared to other CrSBA-15 and CrMCM-41 catalysts.

A much green synthesis method is discovered for the synthesis of t-butyl-p-cresol (TBC), an important used as antioxidant in food industries and the basic raw material for the manufacture of oil-soluble phenol–formaldehyde resins. The TBC is synthesized with a conversion (93.2%) and selectivity (98.6%) through a heterogeneous t-butylation of p-cresol with t-butyl alcohol (t-BuOH) in the liquid phase over mild strong acid catalyst, Zn–Al-MCM-41(75). The catalytic results have also compared with those obtained using other Zn–Al-MCM-41, Al-MCM-41, HY, Hβ, H-mordenite and H-ZSM-5 zeolites. Based on the catalytic results, Zn–Al-MCM-41(75) is found to be a highly active and recyclable heterogeneous catalyst for selective synthesis of TBC.

t-Butylation of 4-methoxyphenol (4-MP) with t-butylalcohol (t-BuOH) as alkylating agent have been conducted under liquid phase reaction conditions over Zn–Al-MCM-41 catalysts with different nSi/(nZn + nAl) ratios for selective synthesis of 2-t-butlylated hydroxyl anisole (2-TBHA). The influences of various reaction parameters such as reaction temperature, time and t-BuOH to 4-MP ratios on the conversion of 4-MP and the selectivity of 2-TBHA have also been studied. With the decrease of the nSi/(nZn + nAl) ratios of Zn–Al-MCM-41 catalysts from 380 to 75, the conversion of 4-MP as well as the yield and selectivity of 2-TBHA increase due to the increase of the number of Bronsted acid sites in Zn–Al-MCM-41 catalysts. The nSi/(nZn + nAl) ratio of 75 is found to be the most suitable and reusable for the t-butylation of 4-MP with t-BuOH for selective synthesis of 2-TBHA.

Prins condensation of β-pinene was carried out with paraformaldehyde in the presence of toluene as solvent over mesoporous Zn-Al-MCM-41 catalysts under liquid phase reaction conditions for synthesis of nopol. The influence of various reaction parameters, such as reaction temperature, time, ratios of reactants and recyclability have been investigated. The catalytic results were also compared with those obtained using Al-MCM-41, HY, Hβ, H-mordenite and H-ZSM-5 zeolites. Zn-Al-MCM-41(75) is then found to be a highly active and recyclable heterogeneous catalyst for selective synthesis of nopol. Furthermore, Zn-Al-MCM-41(75) has higher selectivity of nopol than other Zn-Al-MCM-41, Al-MCM-41, HY, Hβ, H-mordenite and H-ZSM-5.

Highly selective synthesis of diphenylmethane (DPM) was carried out by Friedal–Crafts benzylation of benzene using benzyl chloride (BC) as alkylating agent in the presence of a flow of nitrogen under liquid phase reaction conditions over novel mesoporous SO42−/Al-MCM-41 catalysts with different Si/Al ratios. For these reactions, the influences of various reaction parameters, such as different catalysts, reaction temperature, time, mmol ratios of reactants and recyclability are discussed. With increasing the Si/Al ratios of SO42−/Al-MCM-41 catalysts from 21 to 83, the conversion of BC and selectivity of DPM decreased because the number of Lewis acid sites in SO42−/Al-MCM-41 catalysts are found to decrease almost linearly with increasing ratios of Si/Al. Further the catalytic results were compared with those obtained by using 0.8N sulfuric acid, different Si/Al ratios of Al-MCM-41, HY, Hβ, HM and H-ZSM-5 zeolites. From the comparison of the results, SO42−/Al-MCM-41(21) is found to be a highly active and recyclable heterogeneous catalyst for the highly selective synthesis of DPM. Thus, the selectivity of DPM in SO42−/Al-MCM-41(21) is higher than that in other SO42−/Al-MCM-41 (Si/Al = 42 and 83), Al-MCM-41 (Si/Al = 21, 42 and 83), HY, Hβ, HM and H-ZSM-5.

Aminocyclization reaction of 4-methyl acetophenone (4-MAP) with formaldehyde and ammonia was contacted under vapor phase reaction conditions over novel mesoporous Zn–Al–MCM-41 catalysts with different Si/(Zn + Al) ratios for highly selective synthesis of 2,6-BP (2,6-bis(4-methylphenyl)pyridine). For the reactions, the influences of various reaction parameters such as different catalysts, reaction temperature, reactant molar ratio, WHSV, TOS and recyclability are discussed. With increasing the Si/(Zn + Al) ratios of Zn–Al–MCM-41 catalysts from 75 to 380, the conversion of 4-methyl acetophenone (4-MAP), and the yield and selectivity of 2,6-BP decreased because the number of Bronsted acid sites in Zn–Al–MCM-41 catalysts is found to decrease almost linearly with increasing ratios of Si/(Zn + Al). Further the catalytic results were compared with those obtained by using Al–MCM-41, HY, Hβ, HM and H-ZSM-5 zeolites. The conversion and selectivity is increased in Zn–Al–MCM-41(21) with each cycling of reaction because its catalytic activity does not change. The Si/(Zn + Al) ratio of 21 is found to be more suitable for the aminocyclization reaction of 4-MAP to highly selective synthesis of 2,6-BP. Thus the selectivity of 2,6-BP is higher in Zn–Al–MCM-41(21) than that in other Zn–Al–MCM-41, Al–MCM-41, HY, Hβ, HM and H-ZSM-5.

The mesoporous molecular sieves Al-MCM-41 with Si/Al ratio equal to 16, was synthesized under hydrothermal conditions using cetyltrimethylammonium bromide (CTMA+Br−) as surfactant. The SO 4 2 - /Al-MCM-41(Si/Al = 16) material was synthesized using sulfuric acid under impregnation method, and the resulting material is sulfated Al-MCM-41 ( SO 4 2 - /Al-MCM-41). The mesoporous materials viz. Al-MCM-41 and SO 4 2 - /Al-MCM-41 were characterized using several techniques e.g. ICP-AES, Nephelometer, XRD, FT-IR, TG/DTA, N2-adsorption, solid-state-NMR, SEM, TEM and TPD-pyridine. By impregnating of sulfuric acid on silica surface, crystallinity, surface area, pore diameter and pore volume of SO 4 2 - /Al-MCM-41 decreased except wall thickness. While the Lewis acidity is increased because of the expelling aluminum from the Al-MCM-41 framework by impregnating sulfuric acid. The SO 4 2 - /Al-MCM-41 has been used for synthesis of 2-acetyl-6-methoxynaphthalene using 2-methoxynaphthalene with acetic anhydride as acylating agent and 1,2-dichloroethane as solvent. The catalytic results were compared with those obtained using 0.8 N sulfuric acid, amorphous silica–alumina, H-β, USY and H-ZSM-5 zeolites. From the catalytic results it was concluded that the conversion of 2-methoxynaphthalene and selectivity of 2-acetyl-6-methoxynaphthalene in the SO 4 2 - /Al-MCM-41 is higher than that in other catalysts due to higher number of Lewis acid sites. Thus the SO 4 2 - /Al-MCM-41 is found to be a highly active and recyclable heterogeneous catalyst while the catalyst is a very suitable for the synthesis of 2-acetyl-6-methoxynaphthalene.

t-Butylation of toluene with t-butylalcohol (t-BuOH) as alkylating agent was conducted under liquid phase reaction conditions over Al-MCM-41 with different Si/Al ratios for highly selective synthesis of 4-t-butyltoluene. For the reactions, the influences of various reaction parameters such as reaction temperature, time and t-BuOH to toluene ratio are discussed. With increasing the Si/Al ratios of Al-MCM-41 catalysts from 21 to 104, the conversion of toluene, and the yield and selectivity of 4-t-butyltoluene decreased because the number of Bronsted acid sites in Al-MCM-41catalysts is found to decrease almost linearly with increasing ratios of Si/Al. The conversion and selectivity is increased in Al-MCM-41(21) with each cycling of reaction. The Si/Al ratio of 21 is found to be more suitable for the t-butylation of toluene to highly selective synthesis of 4-t-butyltoluene. Thus the selectivity of 4-t-butyltoluene is higher in Al-MCM-41(21) than that in other Al-MCM-41 samples.

trans -Stilbene oxide have been synthesized under liquid phase reaction conditions using trans -stilbene in the presence of different oxidants and different solvents over synthesized and characterized Zr–Mn-MCM-41 and Mn-MCM-41 as catalysts. On increasing the Si/(Zr + Mn) ratios of Zr–Mn-MCM-41 and Si/Mn ratios of Mn-MCM-41 catalysts from 49 to 327 and 15 to 102, respectively, the conversion of trans -stilbene, yield and selectivity of trans -stilbene oxide decreased. This may be due to the number of Lewis acid sites in Zr–Mn-MCM-41 and Mn-MCM-41 are found to decrease almost linearly with increasing ratios of Si/(Zr + Mn) and Si/Mn, respectively. Both the Zr–Mn-MCM-41(49) and Mn-MCM-41(31) possesses stronger affinity with trans -stilbene and TBHP, but, the conversion of trans -stilbene, yield and selectivity of trans-stilbene oxide decreased in only recyclable Mn-MCM-41. This may be due to decreasing the catalytic activity on the surface of catalysts. In the context, the Si/(Zr + Mn) ratio of 49 is found to be more suitable for the epoxidation of trans -stilbene to highly selective synthesis of trans -stilbene oxide. Thus the yield (76.3%) and selectivity of trans -stilbene oxide (84.58%) are higher in Zr–Mn-MCM-41(49) than that in other Zr–Mn-MCM-41 and Mn-MCM-41 catalysts.

Mesoporous silica molecular sieves MCM-41 containing zinc and aluminum ions (Zn–Al-MCM-41) with Si/(Zn + Al) ratio equal to 75, 151, 228, 304 and 380 and only aluminum ions (Al-MCM-41) with Si/Al ratio equal to 21, 42, 62, 83 and 104 respectively, were synthesized under hydrothermal conditions using cetyltrimethylammonium (CTMA + ) surfactants as template in the absence of auxiliary organics. The mesoporous materials viz. Zn–Al-MCM-41 and Al-MCM-41 were characterized using several techniques. e.g. ICP-AES, XRD, FTIR, TG/DTA, Nitrogen adsorption, 27 Al-MAS-NMR, SEM, TEM, XPS and pyridine acidity (TPD and FTIR) measurements. The d -spacing value and unitcell parameter in the Zn–Al-MCM-41 and Al-MCM-41 decreases by increasing the metal ions content. FT-IR studies showed that zinc ion was incorporated into the hexagonal mesoporous Al-MCM-41 materials, however, the wavenumber of the anti-symmetric Si–O–Si vibration bands (1096 cm −1 ) in Zn–Al-MCM-41 are higher than those in Al-MCM-41 (1083 cm −1 ). These bands should be due to the increase of the mean Si–O distance in the wall caused by the substitution of the small ionic radii of silicon by the larger ionic radii of zinc. The surface area, pore diameter, pore volume of Zn–Al-MCM-41 is smaller than that of Al-MCM-41 while the hydrothermal stability and acid sites in the Zn–Al-MCM-41 are higher than that of Al-MCM-41 due to increasing protons with the aluminum ions non-framework by the introduction of zinc ions. Thus Bronsted and Lewis acid sites in Zn–Al-MCM-41 are same, but its acid sites are higher than Al-MCM-41.

Mesoporous aluminosilicate Al-MCM-41 with Si/Al=93 and 104 were synthesized using cetyltrimethylammonium bromide as the structuring agent and the materials were characterized using several techniques. The mesoporous structure was confirmed by X-ray diffraction (XRD) technique. The surface area, pore size and wall thickness was calculated by BET equation and BJH method using nitrogen sorption technique. Fourier transform-infrared (FT-IR) spectroscopy was used in order to obtain information on incorporated aluminum atoms in the mesoporous structure of Al-MCM-41. Thermogravimetric–differential thermal analyzer (TG–DTA) was used to determine the thermal stability of the materials. The effect of reaction temperature, WHSV and isopropanol:toluene ratios on the selectivity of p-cymene were studied. The Al-MCM-41 (93) catalyst exhibited excellent selectivity in the production of p-cymene by the isopropylation of toluene using isopropanol as the propylating agent.

We have developed a green method for the production of 2,6-disubstituted p-benzoquinones (DSBQs) by liquid-phase oxidations of di/tri-substituted phenols using two-dimensional hexagonally thick-walled mesoporous vanadosilicate catalysts. In particular, 2,6-di-tert-butyl-p-benzoquinone was synthesized by the oxidation of 2,6-di-tert-butylphenol, using various reaction parameters, over mesoporous VSBA-15 catalysts synthesized with various vanadium contents. A promising chemical treatment method for the preparation of green mesoporous VSBA-15(5) or W-VSBA-15(5) (W: washed) catalysts was successfully used in the presence of ammonium acetate solution to remove moderately toxic non-framework V2O5 crystallite species from the active surface, and the catalytic activity of the recovered green mesoporous VSBA-15(5) catalyst was determined. To confirm the green aspects, recyclability and hot-catalytic filtration experiments were performed. The combined results show that the green mesoporous VSBA-15(5) is a highly active, recyclable, and promising heterogeneous catalyst for the selective synthesis of DSBQs (98–100%), and has unprecedented catalytic activity compared with other mesoporous vanadosilicate catalysts.

We approach a green method in the production of alkylaromatic ketones over hexagonally ordered mesoporous CrSBA-15 catalysts, which were used, in green routes, in the liquid-phase oxidation of alkylaromatics. A promising chemical treatment method was used with ammonium acetate solution to remove the toxic nature of non-framework chromium oxides deposited on the surface of calcined CrSBA-15(8), and the obtained green mesoporous CrSBA-15(8) catalyst was used to find its catalytic activity while the recyclability of mesoporous CrSBA-15 catalysts was also studied. Particularly, the mesoporous CrSBA-15 catalysts synthesized with a variety of chromium contents were extensively used in the production of acetophenone (AP=O) with various reaction parameters. On the basis of all catalytic results, the mesoporous CrSBA-15(8) catalyst produced a higher selectivity of alkylaromatic ketones (76-100%) as compared to other CrSBA-15 catalysts and was found to be a highly active, recyclable and promising heterogeneous catalyst for selective synthesis of alkylaromatic ketones.

We demonstrate a much green synthesis method for highly selective synthesis of 6,8-di-t-butylated flavan (6,8-DTBF) by liquid phase alkylation of 2,4-di-t-butylphenol (2,4-DTBP) with cinnamyl alcohol (Cin-OH) over mesoporous Zn–Al–MCM-41 catalysts synthesized under direct basic hydrothermal method. The main alkylated product, 6,8-DTBF is importantly used as an intermediate in the manufacture of biosynthetic organic compounds. The recyclable mesoporous Zn–Al–MCM-41 catalysts have also been reused in this reaction to study their catalytic activities. The influences of various reaction parameters such as temperature, time, ratios of reactant (2,4-DTBP-to-Cin-OH) have been extensively investigated for the synthesis of 6,8-DTBF. In addition, dimethyl sulfoxide (DMSO) has also been used as a solvent in this catalytic reaction. The mesoporous Zn–Al–MCM-41(75) gives excellent catalytic activity with 6,8-DTBF selectivity (86.0%) and 2,4-DTBP conversion (63.1%), and these catalytic results have also compared with that obtained using other mesoporous and microporous catalysts. On the basis of catalytic activity obtained by using the all catalysts, the Zn–Al–MCM-41(75) catalyst is found to be a highly active, recyclable and eco-friendly heterogeneous catalyst in the liquid-phase alkylation of 2,4-DTBP.

Two-dimensional hexagonal thick-walled mesoporous titanosilicate catalysts synthesized using various amounts of titanium were used for the synthesis of 2,3,5-trimethyl-1,4-benzoquinone (TMBO) by liquid-phase oxidation of 2,3,6-trimethylphenol (TMP–OH). These catalysts were also used for the oxidation of di-/tri-substituted phenols to produce 2,6-disubstituted p-benzoquinones (DSBQs). A promising chemical treatment method, for the preparation of green mesoporous TiSBA-15(6) or Washed TiSBA-15(6), was used for removal of non-framework TiO2 nanoparticle species from the active surface, and the catalytic activity of the recovered mesoporous TiSBA-15(6) catalyst has been evaluated. To confirm the green aspects, recyclability and hot-catalytic filtration experiments were performed. Based on the experimental results, it was found that the green mesoporous TiSBA-15(6) is a highly active, recyclable, and promising heterogeneous catalyst for the selective synthesis of TMBO and DSBQs and produces >99% TMBO selectivity with 100% TMP–OH conversion at 353 K for 60 min and 90–100% DSBQs selectivity with 83–99% phenol conversion at 330 K for 1–5 h.

Well hexagonally ordered NbSBA-15 catalysts synthesized by an efficient hydrothermal method were used, for the first time, for the selective synthesis of vitamin K(3) by liquid-phase oxidation of 2-methyl-1-naphthol (2MN1-OH) under various reaction conditions. The recyclable NbSBA-15 catalysts were also reused to find their catalytic activities. To investigate the leaching of non-framework niobium species on the surface of silica networks, the results of original and recyclable NbSBA-15 catalysts were correlated and compared. To find an optimum condition for the selective synthesis of vitamin K(3), the washed NbSBA-15(2.2pH) was extensively used in this reaction with various reaction parameters such as temperature, time and ratios of reactant (2M1N-OH to H(2)O(2)), and the obtained results were also demonstrated. Additionally, the liquid-phase oxidation of 2M1N-OH was carried out with different solvents to find the best solvent with a good catalytic activity. Based on the all catalytic studies, the vitamin K(3) selectivity (97.3%) is higher in NbSBA-15(2.2pH) than that of other NbSBA-15 catalysts, and the NbSBA-15(2.2pH) is found to be a highly active and eco-friendly heterogeneous catalyst for the selective synthesis of vitamin K(3).

Two-dimensional SnSBA-15(CVD) catalyst was synthesized by the chemical vapor deposition (CVD) method using calcined SBA-15 with anhydrous tin(IV) chloride. For comparison studies, two mesoporous tin silicate catalysts, Sn/SBA-15(SC) and Sn/SBA-15(SA) were synthesized under the incipient wetness impregnation (IWI) method using calcined SBA-15 with different tin sources. SnMCM-41(40) was also synthesized by basic hydrothermal conditions. The synthesized mesoporous catalysts were characterized by ICP-AES, XRD, N2 adsorption, UV vis DRS, 29Si MAS NMR, FE-SEM and TEM for the proof of standard mesoporous catalysts with nature of tin on the silica pore walls. For highly selective synthesis of nopol (N–OH), the Prins condensation of β-pinene (PE) with paraformaldehyde (PF-CHO) was performed over different mesoporous catalysts such as SiSBA-15, SnSBA-15(CVD), Sn/SBA-15(SC), SnSBA-15(SA) and SnMCM-41(40), and it was conducted using a variety of optimal parameters such as amount of catalyst, reaction time, reaction temperature, ratios of reactant (PE/PF-CHO), solvents and recycles. In addition, SnSBA-15(CVD) was used in the Prins condensation of PE with PF-CHO in the presence of propyl cyanide (PrCN) with water to investigate its catalytic activity. On the basis of all catalytic results, SnSBA-15(CVD) is found to be a highly active, water-resistant and recyclable heterogeneous catalyst for selective synthesis of N–OH.