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The catalytic properties of Ti–MWW catalysts have been studied for the oxidation of alkenes using hydrogen peroxide or tert -butyl hydroperoxide (TBHP) as an oxidant. Ti–MWW shows superior activity independent of the nature of oxidant when compared to the other Ti-containing catalysts both of microporous TS-1 and Ti-MOR and of mesoporous Ti–MCM-41 in the oxidation of cyclohexene. Compared to large-pore Ti–Beta, Ti–MWW is less active than in the oxidation of cyclohexene using H 2 O 2 , but its shows comparable activity in the case of TBHP. Ti–MWW is very stable in both the structure and the states of Ti species in the actual cycle of reaction–regeneration. The framework B species remaining within the Ti–MWW catalysts seem to have little influence on the intrinsic activity of framework Ti species, but they act as Bronsted acid sites contributing to the hydrolysis of the oxide product to form glycols. The turnover number (TON) of Ti–MWW for the cyclohexene conversion decreases sharply with increasing Ti content, while the TON for the 1-hexene conversion shows volcanic behavior when related to the Ti content. It is clarified that the bulky reaction is catalyzed mainly by the Ti species within the supercages and the exterior pockets of the MWW structure, while in addition to these highly accessible Ti species, those within the channels of a 10-membered ring greatly contribute to the oxidation reactions not significantly sizedemanding.

Grignard reagents were employed for the first time to organically functionalize a mesoporous silica, MCM-41. 29 Si-and 13 C-MAS-NMR spectra proved that Grignard reagents modified the surface of MCM-41, forming stable Si–C bonds from surface silanol groups via alkoxy species without damaging the ordered structure of MCM-41. The degree of organic functionalization depended on the size of the used Grignard reagents. These organically functionalized MCM-41 materials exhibited high hydrophobicity and remarkable hydrothermal stability.

Mo-incorporated SBA-1 mesoporous molecular sieves have been synthesized under acidic conditions using cetyltriethylammonium bromide as a surfactant and used as catalysts for partial oxidation of methane with oxygen as an oxidant. In the partial oxidation of methane the catalytic performance of Mo–SBA-1 materials directly synthesized from the Mo-containing gel were superior to those of Mo-impregnated pure siliceous SBA-1 and amorphous silica.

A selective hydrogen peroxide oxidation of sulfides to sulfoxides using Ti-MWW and Ti-IEZ-MWW catalysts was developed. This reaction was carried out under organic solvent-free conditions, and the only side-product was water. Improvement of catalytic activity toward bulky sulfides will be achieved by optimization of the topology in the Ti zeolite.

Beta zeolite obtained from seeded synthesis without the use of organic structure directing agents (OSDAs) has been used as a catalyst in different types of reactions. The large number of strong acid sites resulted in a high activity for the alkylation of benzene with ethene and a high cracking activity in the hydroconversion of n-decane. However, the high framework polarity resulted in fast deactivation in the acylation of aromatic ethers. Dealumination treatments resulted in improved stability in alkylation reactions with the more reactive olefins like propene. In acylation reactions, the activity was significantly increased, and in hydroconversion, a better balance between the hydrogenation/dehydrogenation and the acid sites was obtained. © 2013 Elsevier Inc. All rights reserved. publisher: Elsevier articletitle: Catalytic applications of OSDA-free Beta zeolite journaltitle: Journal of Catalysis articlelink: http://dx.doi.org/10.1016/j.jcat.2013.05.025 content_type: article copyright: Copyright © 2013 Elsevier Inc. All rights reserved. ispartof: Journal of Catalysis vol:308 pages:73-81 status: published

Titanium silicate-1 (TS-1) samples contained a significant amount of potassium derived from contaminants in an aqueous solution of Pr4NOH. By washing with H2SO4, the alkali-exchanged sites were converted to sites with two OH groups or ‘closed’ Ti(OSi)4 sites. Treatment of the acid-washed samples with an aqueous solution of K2CO3 led to the incorporation of potassium with a K/Ti ratio of around unity, suggesting that K ion exchange on TS-1 corresponds to the presence of Ti in the framework. The potassium ion exchange is considered to occur mainly on the Si–OH group adjacent to the ‘open’ Ti site. The presence of potassium retarded the oxidation of organic compounds with aqueous H2O2 to a different extent depending on the substrates. The retarding effect decreased in the order hexane>2-hexene>2-penten-1-ol and there was little inhibition in the oxidation of 2-penten-1-ol. This could be interpreted in terms of polarities of substrates and active sites in TS-1; non-polar hexane was less easily accessible to the Ti environment made more polar by adjacent potassium. In a similar manner, promotion of the oxidation of the alcoholic group in the reaction of 2-penten-1-ol over the K-type TS-1 might be ascribed to increased interaction of the alcoholic group with the active Ti site.

By IR observation, Lewis acid sites of medium strength were found by CO adsorption on a mesoporous Ta-TMS-1 while no basic sites were detected by CO2 adsorption. Methyl migration of methoxy species and formation of methoxy species from adsorbed dimethyl ether were quantitatively demonstrated.

Highly ordered, titanium-rich organically modified Ti-MCM-41 materials have been synthesized at 413 K using a mixture of organo-triethoxysilane and tetraethyl orthosilicate. Various organic substituents on Ti-MCM-41 used in the present study are methyl, vinyl, allyl, 3-chloropropyl, pentyl, and phenyl. The highest amount of Ti incorporated for a given Si/Ti mole ratio of 30 in the synthesis gel was 33.6 in the case of the 3-chloropropyl group. For methyl, vinyl, allyl, pentyl, and phenyl this ratio varied from 42 to 53, which is considerably lower than for unmodified Ti-MCM-41 reported earlier. Whereas incorporation of short chain organic functionality (C1–C3) causes an increase in the d spacing, resulting in wider pore openings, long chain (pentyl) and aromatic (phenyl) substituents cause a decrease in d spacing in these mesoporous molecular sieves. An increase in the organic content in the synthesis gel beyond a certain level also causes a decrease in d spacing. N2 and H2O adsorption studies revealed that these organically modified well ordered Ti-MCM-41 materials are more hydrophobic than that synthesized in the absence of organic modifiers. These organically modified Ti-MCM-41 materials are efficient catalysts in the epoxidation reaction of unsaturated alcohols followed by cyclization to cyclic ethers using TBHP as oxidant.

Pure silica NU-1 and its titanium silicate analog Ti-NU-1, free from Na and Al, have been synthesized for the first time using the dry gel conversion technique, which was not previously possible under the conventional hydrothermal synthesis procedure. These materials were characterized by XRD, FT IR, UV-vis, TG/DTA, SEM and N 2 adsorption measurements. The presence of a strong framework IR band at ∼960 cm −1 and an UV-vis diffuse reflectance band at 220–240 nm in Ti-NU-1 is an indication of highly dispersed tetrahedral titanium species in the silicate matrix.

Simultaneous surface modification by 3‐chloropropyl and methyl groups on the same Si atoms resulted in hydrophobic and highly ordered mesoporous silica with a very high surface area. 13C and 29Si MAS NMR spectra indicate homogeneous grafting of chloropropyl and methyl groups in the silica matrix and this organically modified Ti‐MCM‐41 shows outstanding catalytic performance in the epoxidation of cyclododecene using tert‐butyl hydroperoxide as oxidant.

In the oxidation of alkanes, Ti-beta catalysts synthesized by the dry gel conversion method show higher turnover number and H2O2 selectivity than the conventionally synthesized ones, which is ascribed to higher hydrophobicity of the former. Trimethylsilylation of mesoporous materials is effective in enhancing the activity through increasing hydrophobicity. It has been revealed that the hydrophobicity of the catalysts whether microporous or mesoporous is a crucial factor in their activity in the liquid-phase oxidation of hydrophobic reactants such as alkanes and simple alkenes using aqueous H2O2 solutions as oxidant.

The vapor Beckmann rearrangement of cyclohexanone oxime to e-caprolactam catalyzed by H-USY with different SiO2/Al2O3 ratios was studied. The catalytic performance of H-USY zeolites for the highly selective formation of e-caprolactam was greatly improved by adjusting the SiO2/Al2O3 ratio and by using an appropriate diluent. It has been found that H-USY catalysts with SiO2/Al2O3 ratios of 27 and 62 exhibited excellent catalytic activity, selectivity and stability when 1-hexanol was used as diluent. The NH3-TPD results indicate that an appropriate amount of relatively weak acid sites of H-USY zeolites are effective for highly selective Beckmann rearrangement. The interaction of alcohols with H-USY zeolites has been investigated by FT-IR to explain the improving effect of 1-hexanol.

Polymerization of lactones such as δ-valerolactone (VL) and e-caprolactone (CL) with protic compounds proceeded in the presence of an aluminosilicate mesoporous zeolite Al-MCM-41 (pore diameter of 27 A, surface area = 1,010 m2 g−1), to give polyesters with narrow molecular weight distribution. The polymerization is likely to proceed via the activated monomer mechanism by the cooperative function of Lewis acidic aluminum and Bronsted acidic silanol functionalities on the interior wall. With titanate-mounted MCM-41 (Ti-MCM-41), the polymerization of VL gave a polymer containing an extremely high molecular weight fraction.

Molybdenum sulfide cluster [Mo 3 S 4 (H 2 O) 9 ] 4+ and nickel–molybdenum bimetallic sulfide cluster [Mo 3 NiS 4 Cl(H 2 O) 9 ] 3+ were incorporated into zeolites NaY, HUSY, NaHβ, Na-mordenite (NaMOR), and KL by aqueous ion exchange. EXAFS data revealed that the structure of the molybdenum sulfide cluster remained virtually intact after ion exchange. However, the incomplete cubane-type structure of the cluster might be lost after thermal treatment at 573 K. The structure of the cluster in Mo 3 S 4 /NaY and Mo 3 S 4 /KL seems to have changed to the MoS 2 -like structure through the hydrodesulfurization (HDS) reaction, although a considerably high level of dispersion was kept. Mo 3 S 4 cluster catalysts loaded on NaMOR and KL exhibited a higher level of activity for HDS of benzothiophene than Mo 3 S 4 catalysts loaded on the other zeolites. Benzene was formed through acid-catalyzed dealkylation of ethylbenzene, the primary HDS product. Alkylation of benzothiophene with alkenes derived from the cracking of decane as the solvent also occurred. The acidity seems to be produced through the ion exchange and reduction of cationic clusters during activation. Over HUSY- and NaHβ-supported catalysts benzene was the major HDS product. Nickel incorporation into the Mo 3 S 4 zeolite catalysts remarkably enhanced the HDS activity. Introduction of the Mo 3 NiS 4 core into zeolite as a precursor resulted in catalysts with higher HDS activity than that of Mo 3 S 4 core and Ni 2+ independently; it is conceivable that the intimate interaction between nickel and molybdenum in the precursor is effective at producing active species.

The epoxidation of alkenes with hydrogen peroxide or molecular oxygen, in the presence of aldehyde catalyzed by heteropolyoxometalate (HPOM) salts and layered double hydroxides (LDHs) containing HPOM anions as pillars, has been investigated. In the case of oxidation with hydrogen peroxide, a lacunary Keggin-ion, SiW 11 O 39 8− , was more active than SiW 12 O 40 4− . For this reaction system using hydrogen peroxide, intercalated SiW 11 O 39 8− showed higher stability in structure and activity than free K 8 SiW 11 O 39 . For the oxidation using molecular oxygen and aldehyde, SiW 12 O 40 4− showed higher activity than SiW 11 O 39 8− . It was confirmed that SiW 12 O 40 4− was intercalated between the brucite-type layers of the LDHs without change in structure. Ni-containing LDHs without any interstitial polyoxometalate showed high activity for the oxidation of cyclohexene with the combination of O 2 and aldehyde.

Open chain unsaturated alcohols 1 , having the general formulaR1R2C=CH(CH2)nCR1R2OH (whereR1,R2=H or CH3, andn=1–3) and carbocyclic unsaturated alcohols of similar type have been efficiently cyclized to the corresponding hydroxytetrahydrofuran or hydroxytetrahydropyran over titanium silicate molecular sieves (TS-1 and Ti-beta), in one pot under mild liquid phase reaction conditions using dilute hydrogen peroxide as oxidant. When the hydroxy nucleophile may attack either of the activated carbon atoms of the epoxides generatedin situ, to lead to a derivative of tetrahydrofuran or tetrahydropyran, the former exclusively formed. The regioselectively for such reaction is 100%. WhenR1orR2=CH3, among the diasteroisomeric productstranspredominates overcis. In this cyclization reaction titanium silicate epoxidizes the olefin and successively catalyzes the opening of the oxirane ring via intramolecular attack of hydroxy oxygen. Thus the behavior of titanium sites is bifunctional in nature. However, for bicyclic unsaturated alcohols, because of geometric restriction, activity of medium pore TS-1 is very low. Ti-beta synthesized by dry gel conversion has been found to be an efficient catalyst in oxidative cyclization of such bulky organic substrates as α-terpineol, isopulegol, andtrans-p-menth-6-ene-2,8-diol to their corresponding tetrahydrofuranols or tetrahydropyranols with a very high regioselectivity.

The structural collapse of mesoporous molecular sieves, MCM-48 and MCM-41 materials by mechanical compression was found to occur mechanochemically through hydrolysis of Si–O–Si bonds. Their ordered structures were retained by compressing the well-dried samples under dry N2. Trimethylsilylation of mesoporous materials proved effective in eliminating their instability to compression through enhancing hydrophobicity.

By aqueous ion exchange, cationic molybdenum sulfide Mo3S44+ clusters have been successfully introduced into KY and KL without destruction of the zeolite structures as verified by the measurements ...

Ti-beta zeolite was synthesized in the presence of sodium cations by a dry-gel conversion method using tetraethylammonium hydroxide as a structure-directing agent. As evidenced by diffuse reflectance UV spectroscopy, incorporated titianium species were tetrahedrally coordinated in the zeolites and neither anatase-like phase nor hexacoordinated titianium species belonging to an amorphous titanosilicate phase was detected at the sodium content of lower than 1.0 mol%. It was found that the Ti-beta catalysts gave very high H2O2conversion and selectivity in the oxidation of cyclohexene in methanol used as solvent. The C6-C8cyclic alkenes and alkanes reacted faster than corresponding linear alkenes and alkanes, showing the lack of steric impediments in the pores of Ti-beta. Dimethylcyclohexanes were more reactive when tertiary H atoms predominantly occupy the equatorial position than when they occupy the axial position. Ti-beta samples exhibited high activity also for the oxidation of C6-C8cyclic alcohols.

Highly dispersed titanium oxide catalysts have been prepared within zeolite cavities as well as in the zeolite framework and utilized as photocatalysts for the reduction of CO 2 with H 2 O to produce CH 4 and CH 3 OH at 328 K. In situ photoluminescence, ESR, diffuse reflectance absorption and XAFS investigations indicate that the titanium oxide species are highly dispersed within the zeolite cavities and framework and exist in tetrahedral coordination. The charge transfer excited state of the highly dispersed titanium oxide species play a significant role in the reduction of CO 2 with H 2 O with a high selectivity for the formation of CH 3 OH, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity to produce CH 4 , being similar to reactions on the powdered TiO 2 catalysts. Ti-mesoporous molecular sieves exhibit high photocatalytic reactivity for the formation of CH 3 OH, its reactivity being much higher than the powdered TiO 2 catalysts. The addition of Pt onto the highly dispersed titanium oxide catalysts promotes the charge separation which leads to an increase in the formation of CH 4 in place of CH 3 OH formation.

Titanium oxide species included within the framework of mesoporous zeolites (Ti-MCM-41 and Ti-MCM-48) prepared by a hydrothermal synthesis exhibited high and unique photocatalytic reactivity for the reduction of CO2 with H2O at 328 K to produce CH4 and CH3OH in the gas phase. In situ photoluminescence, diffuse reflectance absorption, ESR and XAFS investigations indicated that the titanium oxide species are highly dispersed within the zeolite framework and exist in tetrahedral coordination. The charge transfer excited state of the highly dispersed titanium oxide species played a significant role in the reduction of CO2 with H2O exhibiting a high selectivity for the formation of CH3OH.

The large-pore beta zeolite containing Ti has been synthesized in the presence of alkali cations (Na+) by a dry-gel conversion (DGC) technique using tetraethylammonium hydroxide (TEAOH) as a structure-directing agent. The obtained Ti-beta zeolites were compared with hydrothermally synthesized (HTS) Ti-beta. It was found that Ti-beta-DGC samples adsorbed less water (12−13 wt %) than Ti-beta-HTS (19 wt %), indicating that Ti-beta-DGC is more hydrophobic than Ti-beta-HTS. We propose that this leads to a higher activity for the former in the oxidation of cyclohexane. Upon being washed with H2SO4, the turnover number (TON) of DGC samples slightly increased for the oxidation of cyclohexane. DGC and HTS samples demonstrated no significant difference in the activity for oxidation reactions of unsaturated alcohols and C6−C8 cyclic alcohols.

Titanium-containing silicoaluminophosphate (TAPSO-37) with the FAU structure has been synthesized hydrothermally. The TAPSO-37 product was extensively characterized by XRD, infrared spectroscopy (IR), UV–visible spectroscopy (UV–Vis), SEM, solid-state NMR spectroscopy and thermogravimetry. Incorporation of Ti into the SAPO-37 framework resulted in no significant change in the distribution of the silicon species. Ti 4+ ions were most probably isolated and tetrahedrally coordinated in the framework of SAPO-37 crystals, as evidenced by UV–Vis. The stability of TAPSO-37 was studied in detail from room temperature to 973 K. After removal of the template, the structure of TAPSO-37 was remarkably unstable to moisture.

Titanium silicate molecular sieve, TS-1, has been found to be a highly efficient and selective catalyst in dihydroxylation of olefins under triphase reaction conditions in the presence of dilute hydrogen peroxide. Among the substrates unsaturated alcohols (≧C4) give selectively corresponding triol in a very high yield with very high H2O2efficiency. Unsaturated halides give the corresponding diols even at a faster reaction rate. Whereas under the conventional biphase system (in the presence of a cosolvent to homogenize the liquid layers) epoxide is obtained as the major final product in high yield. The substrate nature, i.e., steric hindrance at the active site and hydrophobicity/hydrophilicity of both substrate and epoxide intermediate, is considered to account for the product distribution. Acidity generatedin situover TS-1 in the presence of water (used as the dispersion medium) is responsible for the bifunctional (oxidation and acidic) behavior of the titanium silicate.

Dimethyl carbonate can be synthesized from ethylene carbonate and methanol by using hydrotalcite-type materials as base catalysts. Especially, Mg–Al hydrotalcite-type materials with low Al concentration in brucite-like layers and high OH− proportion in the intercalated anions give high yield of dimethyl carbonate.

Polymerization of lactones such as δ-valerolactone (VL) and e-caprolactone (CL) with protic compounds proceeded in the presence of an aluminosilicate mesoporous zeolite Al−MCM-41 (pore diameter of 27 A, surface area = 1010 m2 g-1, and Si/Al = 17), to give polyesters with a narrow molecular weight distribution. A sequential two-stage polymerization of VL and CL with Al−MCM-41/butanol gave a block copolymer. NMR and GPC studies showed that the produced polymer carries a terminal group originating from the protic compound. In contrast with Al−MCM-41, pure silicate MCM-41, an MCM-41 with masked SiOH functionalities, and a “microporous” aluminosilicate with much narrower pores (zeolite-Y; pore diameter = 8 A) were not effective for the polymerization under similar conditions. Infrared spectroscopy of an inclusion adduct of Al−MCM-41 with VL suggested a possible interaction of the monomer onto the aluminosilicate surface. Al−MCM-41, isolated from the polymerization mixture, could be used again for the polymeriz...

Metallosilicate zeolites containing Ti and V, TS-2 and VS-2, have been synthesized using tetrabutylammonium cation as the template. Although both Ti and V exist in zeolite framework in a highly dispersed state, V easily leaches by K2CO3 or H2O2 treatments in contrast to Ti. Spin trapping experiments and relative reactivity of linear/cyclic alkanes indicate that the oxidation of alkanes over TS-2 and VS-2 proceed by different mechanisms; it is conceivable that the oxidation occurs by way of the attack of ·OH species produced from the V species in the zeolite framework with H2O2.

The vapor‐phase Beckmann rearrangement of cyclohexanone oxime to ɛ‐caprolactam catalyzed by mesoporous molecular sieves was studied. The proton‐form mesoporous molecular sieves, H‐MCM‐41 and H‐FSM‐16, exhibited extremely high activity, selectivity and stability for ɛ‐caprolactam formation when 1‐hexanol was used as diluent. The weak acid sites and/or surface silanol groups of mesoporous molecular sieves play an important role in the selective ɛ‐caprolactam formation.

Free radical polymerization of methyl methacrylate (MMA) within the uniform channels of the mesoporous zeolite MCM-41 proceeds at 100°C to give a high molecular weight polymer (PMMA). The formation of long-living propagating polymer-radicals is observed by electron paramagnetic resonance (EPR). The molecular weight of PMMA within the mesopores can be controlled over a wide range by changing the monomer-to-initiator mole ratio.

The molybdenum sulfide cluster [Mo 3 S 4 (H 2 O) 9 ] 4+ ( 1 ) and the nickel-molybdenum bimetallic sulfide cluster [Mo 3 NiS 4 Cl(H 2 O) 9 ] 3+ ( 2 ) were incorporated into zeolites NaY, HUSY, KL, NaMOR and NaH β by aqueous ion-exchange. The catalysts supported on KL and NaMOR exhibited a higher activity for hydrodesulfurization (HDS) of benzothiophene than catalysts supported on other zeolites. Nickel incorporation into Mo/zeolite catalysts enhanced the HDS activity remarkably. Teh catalysts prepared by ion-exchanging zeolites with 2 were more active in the HDS reaction than the catalysts prepared by ion-exchanging 1 /zeolite with nickel nitrate solution; the presence of the MoSNi linkage in 2 will be effective for producing active HDS species.

The vapor phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam catalyzed by various zeolites was studied. The catalytic performance was greatly affected by both the zeolite structure and diluent solvent. When 1-hexanol was used in place of benzene, the catalytic performance of all catalysts except silicalite-1 was greatly improved. In particular, the selectivity and stability of H-LTL and H-OFF-ERI zeolites remarkably increased; both catalysts exhibited ca. 100% oxime conversion and e-caprolactam selectivity of >95% for 6 h.

The stability of Si-MCM-48 to moisture and compression can be improved by trimethylsilylation, as a result of the increase in hydrophobicity. Moreover, the stability is retained after calcination, although the calcined material is no longer hydrophobic. This stabilizing effect was also observed for Si-MCM-41 and Ti-MCM-41.

Titanium oxide species prepared in the Y-zeolite cavities via an ion-exchange method and those of the Ti-silicalite catalyst prepared hydrothermally exhibit high photocatalytic reactivity for the direct decomposition of NO into N2, O2 and N2O at 275 K with a high selectivity for the formation of N2. The in situ photoluminescence and XAFS investigations indicate that these titanium oxide species are highly dispersed and exist in a tetrahedral coordination in the zeolite cavities and its framework. The charge transfer excited state of these titanium oxide species plays a significant role in the direct decomposition of NO with a high selectivity for the formation of N2, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species and the bulk powdered TiO2 catalyst mainly produce N2O.

Recent developments have been made in the field of new metallozeolites applicable to industrially important catalytic processes. They include the synthesis and characterization of new metallozeolites useful for oxidation reactions. Future development of metallozeolites will be necessary for the improvement in the performance of catalyst systems for application to environmentally benign processes (e.g. oxidation with H 2 O 2 as the oxidant and Beckmann rearrangement) and fine chemical manufacturing.

COE-4 zeolites possess a unique two-dimensional ten-ring pore structure with the Si(OH)2 hydroxyl groups attached to the linker position between the ferrierite-type layers, which has been demonstrated through the interlayer-expansion approach in our previous work (H. Gies et al. Chem. Mater. 2012, 24, 1536). Herein, density functional theory is used to study the framework stability and Brønsted acidity of the zeolite T-COE-4, in which the tetravalent Si is isomorphously substituted by a trivalent Fe, B, Ga, or Al heteroatom at the linker position. The influences of substitution energy and equilibrium geometry parameters on the stability of T-COE-4 are investigated in detail. The relative acid strength of the linker position is revealed by the proton affinity, charge analysis, and NH3 adsorption. It is found that the range of the ⟨T-O-Si⟩ angles is widened to maintain the stability of isomorphously substituted T-COE-4 zeolites. The smaller the ⟨O1-T-O2⟩ bond angle is, the more difficult is to form the regular tetrahedral unit. Thus, the substitution energies at the linker positions increase in the following sequence: Al-COE-4Ga-COE-4Fe-COE-4B-COE-4. The adsorption of NH3 as a probe molecule indicates that the acidity can affect the hydrogen-bonding interaction between (N-H⋅⋅⋅O2) and (N⋅⋅⋅H-O2). The relative Brønsted-acid strength of the interlayer-expanded T-COE-4 zeolite decreases in the order of Al-COE-4Ga-COE-4Fe-COE-4B-COE-4. These findings may be helpful for the structural design and functional modification of interlayer-expanded zeolites.

Ammoximation of cyclic ketones on TS-1 and amorphous SiO2–TiO2with H2O2and NH3was studied. The reactivity of cyclicketones over TS-1 and amorphous SiO2–TiO2showed the following order: cycloheptanone > cyclopentanone > cyclohexanone > cyclooctanone. Shape-selective poisoning studies revealed that the active sites of TS-1 for ammoximation of cycloheptanone are mostly inside the molecular sieve. The reactivity of cyclohexanone and methylcyclohexanones over TS-1 followed the order cyclohexanone > 2-methylcyclohexanone = 3-methylcyclohexanone > 2,6-dimethylcyclohexanone, reflecting the difference in the diffusivity among the reactants or products inside TS-1. Besides the diffusivity the reactivity seemed to be affected by the difficulty in access of the carbonyl group to the Ti active site inside the zeolite; from the comparison of reactivity of dimethycyclohexanone isomers, the steric hindrance of the substituent methyl group to the access of carbonyl group was considered to decrease in the following order: β-equatorial > α-equatorial > β-axial > α-axial. Diffusion of cyclohexanone or its oxime has been found to play an important role in the ammoximation when the TS-1 crystals larger than 1.5 μm were employed as a catalyst. For the TS-1 crystals smaller than 0.3 μm, the ammoximation activity was independent of the diffusivity factor and was determined by the number of active Ti sites present in the zeolite framework.

Zeolites NaY, HUSY and KL were ion-exchanged with a cationic molybdenum sulfide cluster [Mo3S4(H2O)9]4+ with incomplete cubane-type structure and a cationic nickel-molybdenum mixed sulfide cluster [Mo3NiS4Cl(H2O)9]3+ with complete cubane-type structure. The UV-visible spectra and EXAFS analysis data exhibited that the structure of the molybdenum cluster was maintained after ion exchange. These zeolite catalysts showed activity for benzothiophene hydrodesulfurization; especially, involvement of Ni resulted in great enhancement of the hydrodesulfurization activity.

Treatment of Ti−Beta synthesized by the fluoride method with basic quaternary ammonium solution followed by calcination enhanced the epoxidation activity with hydrogen peroxide, which is due to the reduction of the amount of fluorine contained in the catalyst.

The thermal alteration of chlorophyll-a (Chl-a) was examined by means of thermogravimetry (TG) and pyrolysis—gas chromatography (Py-GC). Py-GC/mass spectroscopy, gas chromatography and infrared spectrometry were also used as complementary methods. When pyrolyzed at 340 °C for 15 s, Chl-a produced virtually only C20-isoprenoid hydrocarbons (C20-ISOPs). This result indicates that the major decomposition reaction below 340 °C is the release of a phytyl (3,7,11,15-tetramethyl-2-hexadecenyl) chain. When the 340 °C-pyrolysis residue was pyrolyzed again at 470 °C for 15 s, notable amounts of isoprenoid hydrocarbons with carbon numbers of 19 or less (S-ISOPs) were produced and amounts of C20-ISOPs became smaller. We assume that these S-ISOPs are produced from a phytanylaromatic structure which may have been formed during the 340 °C pyrolysis. On heating Chl-a at 150 °C for a long time (504 h) resulted in the formation of a material barely soluble in many organic solvents. S-ISOPs produced from the barely soluble material upon pyrolysis at 470 °C are similar in molecular distribution to those obtained by the pyrolysis at 470 °C of the 340 °C-pyrolysis residue of Chl-a. This suggests that a phytanyl-aromatic structure is formed also on long-term 150 °C heating. The Chl-a-derived S-ISOPs were almost identical to those obtained upon flash pyrolysis of kerogens (insoluble organic matter in sedimentary rocks) in terms of molecular composition. Thus, it is supposed that Chl-a changes into a polycondensed material having a phytanyl-aromatic structure in sediments/sedimentary rocks and is finally incorporated into a kerogen assemblage in nature.

The effect of clay minerals (montmorillonite and kaolinite) on the thermal alteration of chlorophyll-a (Ch-a) was examined by means of pyrolysis-gas chromatrography. When preliminarily heated at 150 °C for a period ranging from 2 h to 504 h in the presence of montmorillonite or kaolinite, Ch-a produced a considerable amount of material which was insoluble in a 9:1 mixture of iso-octane/ethanol (I/E) but soluble in 3:1 benzene/methanol (B/M). The yield of I/E insoluble-B/M soluble fraction (B/M extract) increased with increased preheating time. Upon pyrolysis, the B/M extract produced isoprenoid hydrocarbons (ISOPs) of carbon number 20 or less. With increased preheating time, the yields of ISOPs of carbon number 20 (C20-ISOPs) dramatically decreased, compared to those of ISOPs of smaller carbon numbers (S-ISOPs). The S-ISOPs were mostly identical to those produced upon pyrolysis of kerogens (insoluble organic matter in sedimentary rocks). The trend in the decrease in the yields of C20-ISOPs with preheating time is similar to that observed for Ch-a preheated in the absence of clay minerals. Clay minerals seem to promote the formation of a structure which preferentially produces 1-pristene (2,6,10,14-tetramethyl-1-pentadecene, Pr-1), the most predominant compound in the ISOPs from kerogens, upon pyrolysis.

Mesoporous silica containing a large amount of aminopropyl groups has been successfully synthesized via the anionic templating route. The electrostatic interaction between the positively charged amino groups in 3-aminopropyltriethoxysilane and the negatively charged sulfate head groups in sodium dodecyl sulfate is a driving force for the self-assembly of silica−micelle composite.

Pt/KL catalysts prepared by ion exchange (IE), ion exchange followed by the addition of KCl (IE-KCl), incipient wetness impregnation (IWI), and coimpregnation with KCl (IWI-KCl) were compared regarding the aromatization of hexane, and were characterized by transmission electron microscopy, the chemisorption of H2 and NH3, the competitive hydrogenation of toluene and benzene, and the infrared spectroscopy of adsorbed CO. The majority of Pt particles on the various Pt/KL catalysts seem to be highly dispersed inside the zeolite channels. The presence of KCl in the Pt/KL catalysts resulted in a decrease in the acidity of zeolite, giving rise to a reduction in the C1–C5 selectivity, regardless of the method of catalyst preparation. The competitive reaction of toluene/benzene and FT-IR results consistently show that the Pt particles on the IE-KCl catalyst have the most electron-rich sites among the Pt/KL samples examined. The high specific activity for benzene production of the IE-KCl catalyst should be attribu...

The influence of the method for loading platinum precursor and adding KCl, KCl loading content, calcination temperature, KCl addition procedure, various additives, and water washing on the activity and selectivity of Pt/KL catalysts for hexane reforming reaction has been investigated. The catalyst preparation methods involve ion exchange (IE), incipient wetness impregnation (IWI), and coimpregnation with KCl (IWI-KCl). The Pt/KL catalysts prepared by ion exchange with [Pt(NH3)4]Cl2 followed by impregnation with KCl (IE-KCl) gave much higher activity and selectivity for benzene formation than the catalysts prepared by coimpregnation of KL zeolite with [Pt(NH3)4]Cl2 and KCl. The IE-KCl catalyst with KCl/Pt molar ratio of 4.5 showed 100.0% conversion of hexane and 89.3% yield of benzene at 743 K and 0.2 MPa. The IE-KCl catalysts exhibited lower H/Pt ratios than the IE catalyst. The KCl addition procedures markedly affected the activity and selectivity of the Pt/KL catalyst; the addition of KCl to the IE sample prior to calcination and reduction was necessary for the catalyst to exhibit the high activity in benzene formation. It has also been found that the performance of Pt/KL catalysts is markedly affected by the calcination temperature. With the IE-KCl catalysts, however, the decrease in the benzene yield caused by high-temperature calcination was not as serious as with the IE catalyst. In contrast, with the IWI and IWI-KCl catalysts, the activity for benzene production was highly sensitive to the calcination at high temperature, drastically decreasing by calcination at 823 K. The Cl species on the IE-KCl catalysts may have existed in the state of KCl.

Ion exchange treatment of Pt/KL catalyst for hexane aromatization with Group 1 or 2 metal salt was carried out to eliminate the effect of acidity induced by H 2 -reduction of the catalyst prepared by ion exchange of KL with [Pt(NH 3 ) 4 ]Cl 2 . The K 2 CO 3 -treated catalyst gave higher conversion and benzene selectivity than the original catalyst Pt/KL. In contrast, no positive effects were observed with the treatment with KCl nor KNO 3 . The low acid strength of the acid site on KL may account for the ineffectiveness of KCl and KNO 3 in neutralizing the protons produced in the reduction process

Potassium salts were added to the catalyst prepared by ion exchange of KL with [Pt(NH3)4]Cl2 and the effect of their counter anion on the activity and selectivity for hexane aromatization was studied. The catalyst to which KF was added showed the highest activity and selectivity for benzene formation; methylcyclopentane and hydroisomerization products were negligible. Although the catalyst with KCl added also exhibited excellent performance, the catalysts with KBr or KI added gave rise to low hexane conversion and benzene yield. Infra-red spectra of adsorbed CO revealed that the presence of the low frequency C-O stretching band is closely related to catalytic performance of the Pt/KL series catalysts. The electron-rich Pt site formed through the interaction with KF or KCl may be responsible for the high activity and selectivity for hexane aromatization.

Optical microscopy, thermogravimetry and stepwise pyrolysis-gas chromatography were applied to three oil shale kerogens. Colorado kerogen, consisting mostly of alginite, gave a sharp d.t.g. peak, whereas Condor and Maoming kerogens, composed of alginite and vitrinite (~ 9:1) gave slightly broader peaks. Step-py-g.c. of all the kerogens gave many peaks of 1-alkene and n-alkane homologues. Condor and Maoming kerogens also gave several moderate g.c. peaks of phenolic compounds, which were hardly seen in the pyrograms of Colorado kerogen. The yields of the phenolic compounds were not strongly dependent on pyrolysis temperature, compared with alkenes and alkanes. The phenolic compounds were thought to be derived from vitrinite. This was confirmed by examining Ozasa vitrinite, for which step-py-g.c. gave large peaks of phenolic compounds similar to those from kerogens in terms of molecular weight distribution and generation profile. These results indicate that maceral composition is an important factor in the pyrolytic behaviour of kerogen.

Thermal decomposition behavior was investigated by use of stepwise pyrolysis—gas chromatography for four oil shales (Colorado, Condor, Maoming and Timhadit oil shales from USA, Australia, China and Morocco, respectively) and their kerogen concentrates. It was revealed that product distribution was dependent on pyrolysis temperature for all the kerogens examined as well as for the oil shales. Isoprenoid hydrocarbons were mostly generated at 430°C from all samples examined, while the majority of 1-alkenes and n-alkanes were generated at 470°C and/or 520°C. Yields of benzene, toluene and xylenes did not significantly change through the stepwise pyrolysis. Based on the pyrolysis behavior, the carbon skeleton structure of kerogen is discussed.