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Infrared spectra of dealuminated high silica MFI zeolites were measured to elucidate the structure of silanol groups active for conversion of 1-butene to propene. The OH groups were replaced by OD groups to have clear vibrational spectra. Two sharp bands and one broad band were observed; isolated silanol at 2746 cm−1, terminal silanol at 2725 cm−1, and hydrogen-bonded silanols centered at 2570 cm−1 composed of more than one components. Based on the response of these bands to Na poisoning and pyridine adsorption together with the correlation with catalytic results, we propose that the active sites for propene formation are one of the terminal silanol groups and one of the hydrogen-bonded silanol groups in a silanol nest. The active hydrogen-bonded silanol groups are the one whose O atom is hydrogen-bonded to adjacent two H atoms in the silanol nest.

Side-chain alkylation of toluene with methanol to form styrene and ethylbenzene was studied over cesium ion-exchanged zeolite X (Cs-X) with various catalyst additives to find out effective catalyst systems for styrene formation as well as to elucidate the roles of the additives. Out of 13 types of additives examined, only ZnO exerted substantial positive effects on both toluene conversion and styrene selectivity. The role of ZnO was estimated to promote conversion of methanol to formaldehyde on the basis of IR study of adsorbed methanol. The formation of formaldehyde accelerated the formation of styrene as well as suppressed the transfer hydrogenation of styrene with methanol to form ethylbenzene. The positive effect of ZnO was also observed for Cs-X containing Cs + in excess of ion-exchange capacity (Cs 2 O-Cs-X). The negative effect of additives such as Al 2 O 3 was suggested to be caused by the formation of CO 2 by water gas shift reaction and Bourdouard reaction.

This chapter covers fundamental aspects of solid acid and base catalysis and applications of solid acid and solid base catalysts in 18 acid- or base-catalyzed reactions. The fundamental aspects include advantage of heterogeneous acid and base catalysis over homogeneous ones in industrial processes, definitions of Bronsted acid and base sites, Lewis acid and base sites, roles of these sites in activating reactant molecules, and characterization methods for these sites. The applications include explanations of representative eleven acid-catalyzed reactions and seven base-catalyzed reactions and catalytic properties of seven solid acid catalysts and four solid base catalysts. Finally, brief perspectives are provided.

Solid base catalysis studied over the last a half of century is reviewed briefly including mainly those performed in our laboratories. The review begins with advantages of solid base catalysts over homogeneous base catalyst in industrial use followed by definition of Brϕnsted base and Lewis base. The materials known as solid base catalysts are listed, and four reasons for which these materials are recognized as solid base catalyst are explained. For all solid base catalysts, variations in activity as a function of pretreatment temperature show a volcano shape; an incline with the temperature results from an appearance of basic sites by removal of water and carbon dioxide from the surface and a decline results from an elimination of basic sites by rearrangement of surface atoms. The reactions catalyzed by solid base catalysts can be classified into three types: double bond isomerization, addition of anion and proton to various double bonds, and alcohol decomposition. These are represented by 1-butene isomerization, hydrogenation of conjugated 1,3-butadiene and dehydration of 2-butanol. Their mechanisms are explained. In addition, bifunctional base-catalyzed reactions in which basic sites participate in one step of successive steps are exemplified for methyl isobutyl ketome synthesis, metathesis, Tishchenko reaction and side-chain alkylation of toluene. Some industrial processes and future perspectives are briefly described.

Reaction of 1-butene was studied over silicalite-1 and H-ZSM-5 zeolites with different Al contents (SiO2/Al2O3 molar ratio (Si/Al2) = 23, 80, and 280) to explore an efficient catalyst for the formation of propene as well as to elucidate the reaction scheme and the relevant acid sites involved in the reaction. The formation of alkenes, including propene, increased and those of alkanes and aromatics decreased with decreasing Al content. The percentage of alkenes other than n-butene isomers was 60 C-wt % over silicalite-1 at 550 °C with 34.1 C-wt % propene. Over H-ZSM-5 with Si/Al2 = 23, the formation of alkenes was negligible, and the main products were alkanes and aromatics, the sum of alkanes and aromatics being 65.4 C-wt % at 550 °C. These product distributions are consistently interpreted by the successive reactions of oligomerization, cracking, and hydrogen transfer. For oligomerization and cracking, in addition to strong acid sites on H-ZSM-5 zeolites, weak acid sites present on silicalite-1 act as ac...

Effects of modification of cesium ion-exchanged zeolite X (Cs-X) with Cs2O and zirconium borate (ZrB2O5) on the catalytic activity in the side-chain alkylation of toluene to styrene and ethylbenzene were studied to prepare an effective catalyst for styrene production. The toluene conversion to styrene and ethylbenzene increased but the selectivity to styrene decreased on modification of Cs-X with Cs2O. For the toluene conversion, the optimum loading of Cs2O was in the range ca. 1–5 wt%. Modification of Cs2O/Cs-X with ZrB2O5 increased both toluene conversion and styrene selectivity. Characterization of acidic and basic properties by IR spectroscopy of adsorbed pyridine and CO2 indicated that basic properties were markedly enhanced but acidic properties were not changed by modification of Cs-X with Cs2O. It is suggested that the enhancement of toluene conversion by modification with Cs2O is due to the generation of strong basic sites which promote the activation of toluene by an abstraction of a proton from methyl group. Modification with ZrB2O5 facilitates the formation of formaldehyde to increase the toluene conversion and suppresses the transfer hydrogenation of styrene with methanol, the main pathway to ethylbenzene, to increase the styrene selectivity.

To control the styrene to ethylbenzene ratio in the products of side-chain alkylation of toluene with methanol over Cs-X-based catalysts, pathway to ethylbenzene was examined. Styrene underwent transfer hydrogenation with methanol much faster than hydrogenation with hydrogen to ethylbenzene. Addition of Cs2O and ZrB2O5 to Cs-X enhanced and suppressed, respectively, the transfer hydrogenation.

Cesium ion-exchanged zeolite X (Cs-X) was modified with metal borates to prepare efficient catalysts for side-chain alkylation of toluene with methanol to styrene. The catalytic behavior of Cs-X was improved by the modification with metal borates such as zirconium borate, zinc borate, copper borate and lanthanum borate. Modification was performed by mechanical mixing of Cs-X and a metal borate in dry state followed by calcination. Significant enhancement of activity was observed for modification with zirconium borate and zinc borate. The selectivity to styrene was increased by modification with all metal borates. Modification with metal component or boron alone was not so effective as that with metal borate. The highest activity was obtained with the Cs-X modified with 10 wt% zirconium borate and calcined at 773 K. The high activity of metal borate-modified Cs-X is due to the ability to selectively form formaldehyde from methanol, which is suggested by appearance of clear IR peak at 1690 cm −1 assigned to unidentate formate species on adsorption of methanol. The basic sites and acidic sites of Cs-X were slightly weakened by modification with metal borates. It was revealed that mechanical mixing of Cs-X and metal borates followed by calcination is a good method to prepare Cs-X modified with both metal components and boron.

An automated microarray diagnostic system for specific IgE using photoimmobilized allergen has been developed. Photoimmobilization is useful for preparing microarrays, where various types of biological components are covalently immobilized on a plate. Because the immobilization is based on a photo-induced radical cross-linking reaction, it does not require specific functional groups on the immobilized components. Here, an aqueous solution of a photoreactive poly(ethylene glycol)-based polymer was spin-coated on a plate, and an aqueous solution of each allergen was microspotted on the coated plate and allowed to dry in air. Finally, the plate was irradiated with an ultraviolet lamp for covalent immobilization. An automated machine using these plates was developed for the assay of antigen-specific IgE. Initially, the patient serum was added to the microarray plate, and after reaction of the microspotted allergen with IgE, the adsorbed IgE was detected by a peroxidase-conjugated anti-IgE-antibody. The chemical luminescence intensity of the substrate decomposed by the peroxidase was automatically detected using a sensitive charge-coupled device camera. All the allergens were immobilized stably using this method, which was used to screen for allergen-specific IgE. The results were comparable with those using conventional specific IgE. Using this system, six different allergen-specific IgE were assayed using 10 μL of serum within a period of 20 min.

Gold nanoparticles supported on γ-alumina and magnesia-doped γ-alumina were synthesized by co-precipitation via a modified sol–gel method. The syntheses were found to produce catalysts with controllable acidity; the presence of either gold or magnesia produced catalyst possessing unbalanced density of acidic and basic sites, while the addition of both gold and magnesia produced catalyst possessing balanced density of relatively stronger acidic and basic sites. The variation of the acid–base strengths of the synthesized catalysts was assessed by using NH 3 -TPD, CO 2 -TPD, and infrared analysis of adsorbed CO 2 and correlated to their catalytic activity in 2-propanol decomposition probe reaction. Catalysts containing magnesia and gold were found to exhibit base catalytic properties through their greater selectivity for acetone formation, while plane γ-alumina and γ-alumina doped with magnesia or gold exhibited acid catalytic properties through their selectivity for propene formation.

The property–activity relationship of WO 3 supported on ZrO 2 (WZ) was evaluated in n -butane isomerization for a series of catalysts with WO 3 loading ranging from 5 to 20 wt% on ZrO 2 . The catalysts were prepared by incipient-wetness impregnation of Zr(OH) 4 with an aqueous solution of (NH 4 ) 6 [H 2 W 12 O 40 · n H 2 O], followed by drying and calcination at 1093 K. The introduction of WO 3 continuously increased the tetragonal phase of ZrO 2 , WO 3 surface density and coverage. The specific surface area and total pore volume passed through a maximum of WO 3 loading at 13 wt%; this loading corresponds to 5.9 WO 3 /nm 2 and is near the theoretical monolayer-dispersed limit of WO 3 on ZrO 2 . The IR results indicate that the presence of WO 3 eroded the absorbance bands at 3738 and 3650 cm −1 corresponding to bibridged and tribridged hydroxyl groups up to near the monolayer-dispersed limit of WO 3 . A new broad and weak band appeared, centered at 2930 cm −1 , indicating the presence of bulk crystalline WO 3 for WO 3 coverage exceeding the theoretical monolayer-dispersion limit. In addition to the band at 2930 cm −1 , two W O stretching bands were observed at about 1021 and 1014 cm −1 for all WZ catalysts, confirming the existence of W O connected to coordinative unsaturated (cus) Zr 4+ through O and to the other W through O, respectively. Pyridine adsorbed IR and NH 3 -TPD revealed that the presence of WO 3 modified the nature and concentration of acidic sites. The highest acidity was observed with 13 wt% loading WO 3 . The decrease in the intensity of peaks due to increasing WO 3 loading was much higher on Lewis acid sites than on Bronsted acid sites. Hydrogen adsorption isotherms and the IR results for hydrogen adsorption on preadsorbed pyridine were used to evaluate the formation of active protonic acid sites from molecular hydrogen. The catalyst with 13 wt% WO 3 loading showed the maximum hydrogen uptake capacity and formation of protonic acid sites. These results show a direct correlation with the activity of WZ in n -butane isomerization at 573 K in which 13 wt% WO 3 loading on ZrO 2 yielded the highest amount of isobutane. It is suggested that the presence of strong Lewis acid sites on monolayer-dispersed WO 3 facilitates the formation of protonic acid sites from hydrogen in the gas phase which act as active sites in n -butane isomerization. The presence of permanent Bronsted acid sites could not be directly associated with activity. In fact, no isomerization activity was observed in the absence of hydrogen.

Pt/WO 3 –ZrO 2 catalysts were prepared under different conditions to optimize the preparative variables for active and selective catalyst in heptane isomerization. The variables examined were (1) pre-drying temperature of hydrous ZrO 2 , (2) way of impregnation, (3) pH of impregnating solution of ammonium metatungstate, (4) WO 3 loading, (5) calcination temperature, (6) calcination atmosphere, and (7) Pt source. In addition to well-known strong effects of (4) and (5), all the variables affected to some extent the activity and selectivity for heptane isomerization. In particular, type of Pt source exerted substantial influence on the activity of the resulting catalyst, H 4 PtCl 6 performing better than Pt(NH 3 ) 4 Cl 2 .

We have developed a polystyrene-based well-of-the-well (WOW) system using injection molding to track individual embryos throughout culture using time-lapse cinematography (TLC). WOW culture of bovine embryos following in vitro fertilization was compared with conventional droplet culture (control). No differences between control- and WOW-cultured embryos were observed during development to the blastocyst stage. Morphological quality and inner cell mass (ICM) and trophectoderm (TE) cell numbers were not different between control- and WOW-derived blastocysts; however, apoptosis in both the ICM and TE cells was reduced in WOW culture (P < 0.01). Oxygen consumption in WOW-derived blastocysts was closer to physiological level than that of control-derived blastocysts. Moreover, WOW culture improved embryo viability, as indicated by increased pregnancy rates at Days 30 and 60 after embryo transfer (P < 0.05). TLC monitoring was performed to evaluate the cleavage pattern and the duration of the first cell cycle of embryos from oocytes collected by ovum pickup; correlations with success of pregnancy were determined. Logistic regression analysis indicated that the cleavage pattern correlated with success of pregnancy (P < 0.05), but cell cycle length did not. Higher pregnancy rates (66.7%) were observed for animals in which transferred blastocysts had undergone normal cleavage, identified by the presence of two blastomeres of the same size without fragmentation, than among those with abnormal cleavage (33.3%). These results suggest that our microwell culture system is a powerful tool for producing and selecting healthy embryos and for identifying viability biomarkers.

Objective— We previously reported a novel technology for the engineering of a capillary network using an optical lithographic technique. To apply this technology to the therapy of ischemic diseases, we tested human omental microvascular endothelial cells (HOMECs) as an autologous cell source and decellularized human amniotic membranes (DC-AMs) as a pathogen-free and low immunogenic transplantation scaffold. Methods and Results— Human umbilical vein endothelial cells were aligned on a patterned glass substrate and formed a capillary structure when transferred onto an amniotic membrane (AM). In contrast, HOMECs were scattered and did not form a capillary structure on AMs. Treatment of HOMECs with sphingosine 1-phosphate (S1P) inhibited HOMEC migration and enabled HOMEC formation of a capillary structure on AMs. Using quantitative RT-PCR and Western blot analyses, we demonstrated that the main S1P receptor in HOMECs is S1P 2 , which is lacking in human umbilical vein endothelial cells, and that inhibition of cell migration by S1P is mediated through an S1P 2 –Rho–Rho-associated kinase signaling pathway. Implantation of capillaries engineered on DC-AMs into a hindlimb ischemic nude mouse model significantly increased blood perfusion compared with controls. Conclusion— A capillary network consisting of HOMECs on DC-AMs can be engineered ex vivo using printing technology and S1P treatment. This method for regeneration of a capillary network may have therapeutic potential for ischemic diseases.

Extensive studies of the cracking catalyst used in the largest process in chemical industries established the research field of solid acid catalysis. Solid acid catalysts are also utilized in various industrial processes. A new concept for acid site generation, Molecular hydrogen-originated protonic acid site, and its characteristics in alkane isomerization are described.

We previously reported a novel optical lithographic technique for the construction of a capillary network consisting of endothelial cells. To investigate the feasibility of clinical application in the treatment of ischemic diseases, capillary structures were formed on scaffolds made from amniotic membrane (AM) and implanted into mice. The capillary network remained in place for at least 5 days and blood perfusion through the implanted capillaries was histologically detected in an ear flap model. Moreover, blood was observed flowing through the capillary network implanted in abdominal subcutaneous tissue of mice at 5 days after insertion. Implantation of the AM capillary structure into the ischemic hind limbs of mice significantly increased reperfusion compared with controls (AM only). Blood flow was restored in the ischemic limbs to the level of corresponding nonischemic limbs as early as 9 days after surgical implantation. The treatment reversed ischemic symptoms, and ambulatory impairment was significantly improved. Thus, the implantation of a capillary network engineered ex vivo could have therapeutic potential for ischemic diseases.

The rate controlling step and the energy barrier involved in the hydrogen adsorption over Pt/MoO3 were studied. Rates of hydrogen adsorption on Pt/MoO3 were measured at the adsorption temperature range of 323–573 K and at the initial hydrogen pressure of 6.7 kPa. The rate of hydrogen uptake was very high for the initial few minutes for adsorption at and above 473 K, and reached equilibrium within 2 h. At and below 423 K, the hydrogen uptake still continued and did not reach equilibrium after 10 h. The hydrogen uptake exceeded the H/Pt ratio of unity for adsorption at and above 423 K, indicating that hydrogen adsorption involves hydrogen atom spillover and surface diffusion of the spiltover hydrogen atom over the bulk surface of MoO3 followed by formation of HxMoO3. The hydrogen uptake was scarcely appreciable for Pt-free MoO3. The rate controlling step of the hydrogen adsorption on Pt/MoO3 was the surface diffusion of the spiltover hydrogen with the activation energy of 83.1 kJ/mol. The isosteric heats of hydrogen adsorption on Pt/MoO3 were 18.1–16.9 kJ/mol for the hydrogen uptake range 2.4–2.8 × 1019 H-atom/g-cat. Similarities and differences in hydrogen adsorption on Pt/SO42−–ZrO2, Pt/WO3–ZrO2 and Pt/MoO3 catalysts are discussed.

Contents The purpose of this study was to assess the feasibility of polyester mesh culture for the in vitro production of bovine embryos, as polyester mesh is an alternative way for tracking individual embryos throughout culture using time-lapse cinematography (TLC). Bovine embryos were isolated during in vitro culture using sections of three different polyethylene terephthalate (PET) mesh products. In vitro matured and fertilized bovine oocytes were cultured in the 217 × 217, 230 × 230 or 238 × 238-μm openings of PET mesh sections or in simple micro-drops (control) for 7 days under either 20% or 5% O2 tensions. No difference in embryo developmental rates was found between the culture groups in terms of cleavage, blastocyst formation and blastocyst expansion irrespective of O2 tension. In contrast, under 20% O2 tension, blastocysts that developed in PET mesh with 217 × 217-μm opening had significantly higher numbers of total and trophectoderm (TE) cells than control embryos; however, the numbers and proportions of inner cell mass (ICM) cells did not differ. Under 5% O2 tension, no difference was found among the culture groups in the numbers of total, ICM and TE cells in embryos. All three PET mesh products investigated in this study were proven to be effective to prevent embryo movement. The results demonstrate that bovine embryos can be cultured in PET mesh sections without negative side-effects and suggest that embryo distance determined by the mesh affects embryo quality at atmospheric oxygen tension. Polyethylene terephthalate mesh with 217 × 217-μm openings was found to be the most suitable for further application in TLC.

We made micropatterned vascular endothelial cells, which have a regular capillary tube-like structure, on a bioactive hydrogel matrix. We applied a stamping method to transfer micropatterned bovine aortic endothelial cells to a growth factor-reduced basement membrane matrix (Matrigel) and type I collagen gel. In this study, we addressed the issues of how to accelerate cell transfer and the effective factors in doing so. We focused on the effects of the cell-substratum and cell-cell adhesiveness prior to applying cultured endothelial cells to a hydrogel matrix on cellular behavior under transfer printing. We found that individual cells cultured sparsely on substrata with different cell adhesivity transferred to Matrigel up to 40%, whereas cells cultured on patterned substrata having lines of 60 mum in width, which involved cell-cell contacts, could transfer homogeneously to Matrigel within a few hours. The morphology of such cells changed from a tape-like monolayer into a thinner, tube-like structure. The speed and the ratio of transfer of micropatterned cells to Matrigel were affected by the period of cell culture on micropatterned substrata. We also found that the intensity of vascular endothelial cadherin staining at cell-cell junctions of micropatterned cells was correlated with cellular behavior when applying them to Matrigel, on which cells formed a tube-like structure or to which cells migrated individually. Furthermore, micropatterned cells made regular tube-like structures when applied to type I collagen gel. Such tube-like endothelial cells had good viability. These findings may be useful for creating in vitro angiogenesis assays and tissue-like constructs that include capillary-like networks of vascular endothelial cells.

The selective oxidation of ethene to acetic acid in the vapor phase over solid acid-supported Pd catalyst was investigated to elucidate the reaction mechanism and the roles of Pd and acidic sites in promoting the reaction. Two catalysts, Pd–H 4 SiW 12 O 40 /SiO 2 and Pd/WO 3 –ZrO 2 , exhibited high catalytic activity. Variations in product distribution with contact time, the requirement for the presence of water vapor for the reaction to occur, and the reactivities of possible reaction intermediates indicated that acetic acid is formed via an acetaldehyde intermediate which is produced in a Wacker-type reaction, while the role of the acid sites is to re-oxidize Pd 0 into Pd 2+ in the presence of O 2 . It was concluded that catalytic efficiency is dependent on maximization of the interface between metallic Pd and acidic surface by establishing an appropriate ratio of Pd and acidic sites.

The rate determining step and the energy barrier involved in hydrogen adsorption on Pt/WO 3 - ZrO 2 were studied based on the assumption that the hydrogen adsorption occurs only through Pt sites. The rate of hydrogen adsorption on Pt/WO 3 -ZrO 2 was measured in the adsorption temperature range of 323–573 K and an initial hydrogen pressure of 50 Torr. The rates of hydrogen uptake were very high for the initial few minutes and the adsorption continued for more than 5 h below 523 K. The hydrogen uptake far exceeded the H/Pt ratio of unity for all adsorption temperatures, indicating that the adsorption of hydrogen involved the dissociative adsorption of hydrogen on Pt sites to form hydrogen atoms, the spillover of hydrogen atoms onto the surface of the WO 3 -ZrO 2 catalyst, the diffusion of spiltover hydrogen atom over the surface of the WO 3 -ZrO 2 catalyst, and the formation of protonic acid site originated from hydrogen atom by releasing an electron in which the electron may react with a second hydrogen atom to form a hydride near the Lewis acid site. The rate determining step was the spillover with the activation energy of 12.3 kJ/mol. The rate of hydrogen adsorption cannot be expressed by the rate equation based on the assumption that the rate determining step is the surface diffusion. The activity of Pt/WO 3 -ZrO 2 was examined on n-heptane isomerization in which the increase of hydrogen partial pressure provided positive-effect on the conversion of n-heptane and negative-effect on the selectivity towards iso -heptane.

Tissue engineering approaches have been developed for vascular grafts, but success has been limited to arterial replacements of large-caliber vessels. We have developed an innovative technique to transplant engineered capillary networks by printing techniques. Endothelial cells were cultured on a patterned substrate, in which network patterns were generated by prior optical lithography. Subsequently, the patterned cells were transferred to extracellular matrix and tissue at which point they changed their morphologies and formed tubular structures. Microinjection of dye showed that the micrometer-scale tubular structure had in vitro flow potential. When capillary-like networks engineered on amnion membranes were transplanted into mice, we found blood cells inside of the lumen of the transplanted capillary-like structure. This is the first report of the in vitro formation of capillary networks using cell transfer technique, and this novel technique may open the way for development of rapid and effective blood perfusion systems in regenerative medicine.

Solid base catalysis studied over the last a half of century is reviewed briefly including mainly those performed in our laboratories. The review begins with advantages of solid base catalysts over homogeneous base catalyst in industrial use followed by definition of Brϕnsted base and Lewis base. The materials known as solid base catalysts are listed, and four reasons for which these materials are recognized as solid base catalyst are explained. For all solid base catalysts, variations in activity as a function of pretreatment temperature show a volcano shape; an incline with the temperature results from an appearance of basic sites by removal of water and carbon dioxide from the surface and a decline results from an elimination of basic sites by rearrangement of surface atoms. The reactions catalyzed by solid base catalysts can be classified into three types: double bond isomerization, addition of anion and proton to various double bonds, and alcohol decomposition. These are represented by 1-butene isomerization, hydrogenation of conjugated 1,3-butadiene and dehydration of 2-butanol. Their mechanisms are explained. In addition, bifunctional base-catalyzed reactions in which basic sites participate in one step of successive steps are exemplified for methyl isobutyl ketome synthesis, metathesis, Tishchenko reaction and side-chain alkylation of toluene. Some industrial processes and future perspectives are briefly described.

Tishchenko reaction of benzaldehyde was carried out over the MgO whose surface O atoms were enriched with 18 O to examine whether the surface O atoms of MgO are incorporated into the product and reactant. The surface lattice 18 O atoms were incorporated in both the product and reactant. The 18 O concentration was significantly higher for the product than for the reactant. In addition, the 18 O in the product ester was located not only in the carbonyl group (C O) but also in the bridging position (C O C); 18 O exchange between benzaldehyde and MgO surface occurred not only in the adsorption–desorption of benzaldehyde, but also in the dimerization process. The oxygen exchange results in the migration of active sites of coordinative unsaturated site (CUS) over the surface of MgO catalyst during the reaction.

H 2 adsorption over two Pt/SO 4 2--ZrO 2 (Pt/SZ) samples pretreated under different conditions (one is catalytically active and the other is inactive in n-butane isomerization) was investigated by in-situ Fourier transforminfrared (FTIR) spectroscopy and temperature-programmed desorption (TPD). It was found that the formation of H 2 O was the crucial difference between the active and inactive Pt/SZ samples upon H 2 adsorption at 523 K, with isolated zirconium OH groups forming on both samples. Under the same conditions, neither H 2 O nor zirconium OH groups formed on SO 4 2--ZrO 2 (SZ), and only a small amount of OH groups formed on Pt/ZrO 2 . CO adsorption results reveal the presence of both Bronsted and Lewis acid sites on the surface of Pt/SZ, as well as the transformation of Lewis acid sites to Bronsted acid sites upon H 2 adsorption at 523 K. These results present direct evidence of H 2 spillover from Pt to the sulfated zirconia surface. The formation mechanism of H 2 O and OH groups is discussed, and it is suggested that the active oxygen species, which should be associated with the intermediate sulfate species on the active Pt/SZ surface, plays an essential role as active sites on Pt/SZ in n-butane isomerization.

The oxygen exchange between surface carbonate species and oxide surfaces was investigated by the temperature-programmed desorption (TPD) of C18O2 adsorbed on metal oxides, MgO, CaO, and ZrO2 at room temperature. Although desorption plots were quite different for these metal oxides, extensive oxygen exchange was commonly observed. The fraction of C16O2 in the total desorbed CO2 increased monotonically with desorption temperature, and each desorption peak in the plots for the total CO2 could not be characterized by the isotopic distribution. The difference in proportion of incorporated lattice oxygen in the total CO2 at each desorption temperature was small between the low and high concentrations of C18O2. Among these metal oxides, ZrO2 showed the highest fraction of C16O2 in the total CO2 desorbed at 400 °C when C18O2 was adsorbed on these metal oxide with same surface concentration. The value of [C16O18O]2/{[C16O2][C18O2]} was close to 4 over almost all the temperature region of desorption for all these m...

The mechanism of the generation of protonic acid sites from molecular hydrogen on WO3-ZrO2 was studied by IR spectroscopy. The spectral changes in the WO stretching and the OH stretching regions were observed in response to the exposure to hydrogen and the removal of hydrogen. By heating in the presence of hydrogen, the WO stretching bands at 1021 and 1014 cm−1 eroded and a broad band around 980 cm−1 was developed. The peaks at 1021, 1014 and 980 cm−1 restored to their original intensities on heating in a vacuum. A broad OH stretching band around 3600 cm−1 was intensified by heating in the presence of hydrogen and restored to its original intensity by removal of the hydrogen from a gas phase. Pyridine adsorption caused essentially the same changes in the WO stretching region as hydrogen adsorption. Based on the spectral changes, the changes in the structure of acid sites caused by hydrogen adsorption are proposed.

Rates of hydrogen adsorption on Pt/WO3-ZrO2 and WO3-ZrO2 were measured in the adsorption temperature range 323–573 K and the hydrogen pressure range 20–70 Torr (1 Torr = 133 Pa) to elucidate the rate-controlling step involved in the hydrogen adsorption, the corresponding energy barrier, and the heat of adsorption. The hydrogen adsorption was faster on Pt/WO3-ZrO2 than on WO3-ZrO2. On both Pt/WO3-ZrO2 and WO3-ZrO2, the adsorption continued for a long time. The adsorption continued for more than 10 h for Pt/WO3-ZrO2 below 373 K and for WO3-ZrO2 below 473 K. The adsorption of hydrogen involved the surface diffusion of hydrogen atoms for both adsorbents. For WO3-ZrO2, each hydrogen molecule was dissociated on a specific site of WO3-ZrO2 to form hydrogen atoms, which undergo surface diffusion over the surface of WO3-ZrO2. The rate-controlling step was the surface diffusion of hydrogen atoms. The activation energy was 25.9 kJ/mol for the surface diffusion. For Pt/WO3-ZrO2, two routes were operating. One route was same as that for WO3-ZrO2, and the other route involved dissociation of hydrogen molecules on the Pt sites to form hydrogen atoms that undergo spillover onto the WO3-ZrO2 surface, followed by surface diffusion. For the latter route, the rate-controlling step was the spillover step; its activation energy was 35.5 kJ/mol. The isosteric heats of adsorption of hydrogen on Pt/WO3-ZrO2 were obtained as 11.6–8.0 kJ/mol for the hydrogen uptake range 2–3×1019 atom H/g cat. Similarities and differences in hydrogen adsorption between SO42−-ZrO2 and WO3-ZrO2 types are discussed.

An efficient, economical, and environmentally benign method for the synthesis of phthalide–skeleton using heterogeneous catalytic intramolecular Tishchenko reaction with solid bases is described. Among the solid base catalysts examined, MgO, CaO, and SrO exhibited high catalytic performances for the intramolecular Tishchenko reaction of o-phthalaldehyde to yield phthalide exclusively in excellent yields at 313 K in the short time span of 0.25 h. Application of γ-alumina to the intramolecular Tishchenko reaction of o-phthalaldehyde was also successful; phthalide was obtained selectively in excellent yields at 313 K in 4 h. The employment of KF/alumina and KOH/alumina at 313 K for 4 h resulted in the selective formation of phthalide in moderate yields. The heterogeneous catalytic systems realized by the use of CaO and γ-alumina were also successfully applicable to the selective intramolecular Tishchenko reaction of 2,3-naphthalenedicarbaldehyde to give the corresponding five-membered lactone in excellent yields at 333 K for 2 and 20 h, respectively. Based on the reaction results, the infrared spectra of adsorbed o-phthalaldehyde, and the quantum chemical calculations conducted at the PM3-MO level of theory for elucidation of the molecular and electronic structures of o-phthalaldehyde and the potential intermediates, a plausible reaction mechanism for the intramolecular Tishchenko reaction of o-phthalaldehyde to phthalide over MgO and γ-alumina was proposed. The catalytically active species should be o-MOCH2C6H4CHO (M=Mg or Al).

Nitroaldol reaction of a nitro compound with a carbonyl compound was carried out over a variety of solid base catalysts to elucidate the activity-determining factors in the nature of the catalysts and in the nature of nitro and carbonyl compounds. Among the catalysts examined, MgO, CaO, Ba(OH) 2 , KOH/alumina, KF/alumina, Sr(OH) 2 , hydrotalcite, and MgCO 3 exhibited high activity for nitroaldol reaction of nitromethane with propionaldehyde, the activities being in this order. Over these catalysts, the yields exceeded 20% at a reaction temperature of 313 K and a reaction time of 1 h. Mg(OH) 2 , γ-alumina, SrO, Ca(OH) 2 , BaCO 3 , SrCO 3 , BaO, and La 2 O 3 exhibited moderate activites; the yield were in the range 20–2%. CaCO 3 , ZrO 2 , and ZnO scarcely showed the activity. It is suggested that strongly basic sites are not required for the reaction because the abstraction of a proton from a nitro compound is easy. The reactivities of the nitro compounds were nitroethane > nitromethane > 2-nitropropane, and those of carbonyl compounds were propionaldehyde>isobutyraldehyde>pivalaldehyde>acetone>benzaldehyde>methylpropionate. On the basis of IR study of adsorbed reactants and the reactivities of the reactants, the reaction mechanisms are proposed. The reaction proceeds by the nucleophilic addition of the carbanion formed by the abstraction of a proton from nitro compounds to the cationic species formed by the adsorption of carbonyl compounds on the acidic sites (metal cations). The nitroaldol reaction of nitromethane with propionaldehyde over MgO was scarcely poisoned by carbon dioxide and water; nitromethane is so acidic that it is able to be adsorbed on the catalyst on which carbon dioxide or water was preadsorbed.

Properties of acidic sites on WO 3 –ZrO 2 and Pt/WO 3 –ZrO 2 were studied. The IR results of adsorbed pyridine were related to effects caused by contact with hydrogen. For both WO 3 –ZrO 2 and Pt/WO 3 –ZrO 2 , the ratio of Lewis acid sites to protonic acid sites increases with an increase of the temperature of pretreatment with hydrogen followed by outgassing. All of the protonic acid sites were strong; pyridine molecules remain on the protonic acid sites after outgassing at 673 K. In addition to strong Lewis acid sites, there existed a number of weak Lewis acid sites from which pyridine molecules were desorbed in the temperature range 423–673 K. When WO 3 –ZrO 2 and Pt/WO 3 –ZrO 2 were heated in hydrogen, protonic acid sites were formed with a concomitant decrease of Lewis acid sites. The protonic acid sites thus formed were eliminated by heating in a vacuum, with restoration of Lewis acid sites. The presence of Pt facilitated the interconversion between Lewis acid sites and protonic acid sites; with Pt/WO 3 –ZrO 2 , the formation and elimination of the protonic acid sites occurred even at room temperature. Hydrogen dissociation monitored by H 2 –D 2 exchange took place over WO 3 –ZrO 2 above 373 K, and was strongly retarded by pyridine preadsorption. These results indicate that the active sites for hydrogen dissociation on WO 3 –ZrO 2 are acidic sites.

Catalytic behavior of solid bases for mixed Tishchenko reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The reactions were performed at 353 K for 4 h in vacuo without solvent using 5 mmol of each aldehyde and 100 mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaO≪MgO

Hydrogen adsorption was studied for Pt/SO42--ZrO2 samples modified with Na addition, pyridine preadsorption, and water preadsorption to elucidate the relation between the rate and capacity of hydrogen adsorption and the surface state. The surface states were monitored by XRD, IR, ammonia TPD, and measurement of catalytic activity for cyclohexane isomerization. All the modifications suppressed the hydrogen uptake. It was suggested that Lewis acid sites promote the hydrogen uptake by stabilizing spiltover hydrogen atoms.

Catalytic behaviors of solid base catalysts for mixed Tishchenko reactions were investigated to elucidate the activity- and selectivity-determining factors in active sites of the catalysts and molecular structures of the reactants. A mixture containing equal amounts of two kinds of aldehydes was allowed to react at 353 K. The aldehydes used were benzaldehyde, pivalaldehyde, and cyclopropanecarbaldehyde. For all the reactions, the catalytic activity of alkaline earth oxides increased in the order of BaO⪡MgO

Studies of solid base catalysts on generation of basic sites and their catalytic behaviors in organic reactions performed in our group are summarized. For most of the materials called solid base, the catalytic activities appear on removal of water and carbon dioxide from the surfaces. The nature of the surface basic sites varies with severity of pre-treatment conditions. Besides removal of water and carbon dioxide, rearrangement of surface and bulk atoms occurs during pre-treatment, which changes the number and nature of the basic sites with increasing the pre-treatment temperature. Therefore, the optimum pre-treatment temperature varies with the type of reaction. Applications of solid base catalysts to the following reactions are described; (1) double bond isomerization, (2) hydrogenation, (3) amination, (4) dehydrocyclodimerization, (5) aldol addition, (6) nitroaldol reaction, (7) Michael addition, (8) conjugate addition of alcohol, (9) cyanoethylation, and (10) Tishchenko reaction. Characteristic features of the solid base catalysts toward these reactions are briefly explained. Finally, selected base-catalyzed reactions which have been industrialized by use of solid base catalyst are exemplified, and short comments on the catalysts used in these processes are made.

The photoinduced behaviour of low molecular mass liquid crystalline (LC) systems doped with the chiral photochromic spiro-oxazine, 9'-{5-(-)-menthoxyacetoxy-1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3'-[3H]naphth-[2,1 -b][1,4]oxazine]} 4-[11-(tetrahydro-2-pyranyloxy)undecyloxy]biphenyl-4'-carboxylate (THP11SOM) was observed by means of transmittance measurements at 21°C. The experimental results revealed that the ring-opened merocyanine form of THP11SOM resulting from the photochromism first disturbed the helical planar orientation of the LC molecules and then induced a new helical pitch. The magnitudes of both the disturbance in orientation of the LC molecules and the shift in the helical pitch were significantly influenced by the concentration of THP11SOM. The photoinduced behaviour was reversible due to the photochemical and thermal back reaction of the THP11SOM. In addition, the effect of UV light on the nematic-isotropic transition temperatures of the mixtures with or without a hindered amine ligh...

Conjugate addition of methanol to 3-buten-2-one to form 4-methoxy-butan-2-one proceeds effectively over the solid base catalysts such as alkaline earth oxides, strontium hydroxide, barium hydroxide, and alumina supported potassium fluoride and hydroxide at a reaction temperature of 273 K. The catalytic activities of magnesium oxide, calcium oxide, and alumina supported KF catalyst were not much affected by exposure of the catalysts to carbon dioxide or air.

Two-step assembly (TSA) technique for preparation of polymer-particle composite films is presented. The TSA process consists of coating a polyelectrolyte onto a substrate and dipping the coated substrate in a particle suspension. The previously coated polyelectrolyte acts as a particle aggregation promoter, in other words, as an adhesive for particles. Diffusion and adsorption of the polyelectrolyte are important behaviors for this process. Preparation of composite films consisting of commercially available polyelectrolytes such as poly(diallyldimethylammonium chloride) (PDDA) and colloidal silica (SiO 2 ) or titania (TiO 2 ) particles were demonstrated. The composite films were porous and their thickness depended on the thickness and the molecular mass of previously coated polyelectrolyte, treatment time, and the concentration of suspension. Some PDDA-SiO 2 composite films with 190 nm SiO 2 particles had colloidal crystal domains and reflected visible light.

The addition of calcium sulfate in the procedures of preparing flue gas desulfurization absorbent from calcium oxide and coal fly ash causes a negative effect in the slaking step and a positive effect in the following hydrothermal treatment step. The role of calcium sulfate added in each step was investigated. For the slaking step, XRD, XAFS, and Raman spectroscopic studies revealed that the addition of calcium sulfate in the step of slaking CaO with coal fly ash resulted in the coverage of calcium hydroxide with calcium sulfate to decrease the reactivity of the calcium hydroxide toward coal fly ash to form calcium silicate. For the hydrothermal treatment step, measurements of XRD, surface area, and Raman spectrum revealed that the addition of calcium sulfate promotes the formation of calcium silicate by suppressing crystal growth of calcium hydroxide to keep the reactivity of the calcium hydroxide toward coal fly ash.

Effects of solvent hydrotreatment on product yields in the NEDOL coal liquefaction process were examined based on the data obtained by a 150 t/d pilot plant operation. When the hydrogen gas consumption in the liquefaction stage was kept constant at 4.7 wt.%-daf (wt.% on the basis of dry and ash-free coal), the yield of the oil fraction increased from 51.0 to 54.9 wt.%-daf with an increase in the hydrogen gas consumption from 0.7 to 1.3 wt.%-daf in the hydrotreatment stage. In the hydrotreatment stage, about 30% of the hydrogen consumed was utilized for enrichment of naphthenic hydrogen content in the solvent, and the rest was used for both the removal of nitrogen from the solvent and the production of the light oil fraction. In the liquefaction stage, the hydrogen donated from the solvent was more efficiently utilized than the gaseous hydrogen for the production of the oil fraction. Under the conditions that the total hydrogen consumption in the hydrotreatment and liquefaction stages was kept constant, the yield of oil fraction and the nitrogen content in oil fraction were higher when the hydrogen consumption in the liquefaction stage increased with concomitant decrease in the hydrotreatment stage.

Contamination and a degree of deactivation of Ni–Mo/γ-Al2O3 catalyst used for solvent hydrotreatment in a coal liquefaction process were examined based on the data obtained from a 150 ton/day pilot plant. When solvent hydrotreatment was carried out at 300°C, the Fe, Ca, and Si contents of the catalyst used for 3200 h were higher than those for 500 h. The Fe contaminant tended to be greatly concentrated near the edge of the catalyst grain. Pore volumes of the catalysts used for 3200 and 500 h were 0.34 and 0.39 ml/g, respectively. The catalyst used at 325°C for 2800 h contained more Fe than that at 300°C for 3200 h. No difference in carbon content was obvious among the three used catalysts. In the down-flow fixed bed hydrotreater, Fe content was larger while the pore volume was less upstairs. In solvent hydrotreatment at 300°C, the degree of deactivation was 20% after 3200 h. When solvent hydrotreatment was carried out at 325°C, the degree of deactivation reached 25% after 2800 h. The amount of contaminants are compared in relation to the degree of deactivation, and mechanisms on catalyst deactivation in the solvent hydrotreatment are discussed.

Rate of hydrogen adsorption on sulfated zirconia-supported platinum (Pt/SO4 2 ‐ZrO2) was measured in the temperature range 323‐523 K to elucidate the slowest step involved in the hydrogen adsorption and the corresponding energy barrier which the hydrogen species should cross over. At a nearly constant hydrogen pressure (50 Torr (6.7 kPa)), the hydrogen uptake continued more than 24 h, and the uptake in 24 h increased with an increase in the adsorption temperature. Above 473 K, the hydrogen uptake far exceeded the H/Pt ratio of unity, indicating that the hydrogen adsorption involves hydrogen spillover. Without Pt, the hydrogen uptake was scarcely appreciable. The hydrogen adsorption rate followed the Fick’s equation for surface diffusion. Activation energy for the diffusion constant was obtained as 84 kJ/mol. The rate could not be expressed by the rate equation derived on the assumption that the rate controlling step is the spillover step. © 2000 Elsevier Science B.V. All rights reserved.

A modification of our previous equation for estimation of the molar volume of hydrocarbons on the basis of atomic group contributions was made to be able to extend the applicability to a wide variety of hydrocarbons, including condensed polyaromatic hydrocarbons (CPAHC), which are main components in heavy oils. Two atomic groups were additionally selected to characterize CPAHC, namely aromatic conjunction (ac) and aromatic inner (ai) carbons. Utilizing the molar volume data for pure CPAHC in literature, increments in the molar volume by the presence of the two groups were evaluated by a regression analysis as 2.8 and 8.6 ml/mol, respectively. The molar volumes of hydrocarbon mixtures in heavy oils containing CPAHC, estimated with the above increments, agree well with those observed. The equation is applicable to polyaromatic hydrocarbons with the ring numbers up to seven in both forms of pure substances and their mixtures.