The Catalytic Conversion of 1,2-Propandiol to Propanal on FSM-16 Molded by Wet-Treatment and Pressurization

The catalytic conversion of 1,2-propandiol to propanal is examined using FSM-16 particles (0.85－1.70 mm) molded by wet-treatment and pressurization. When FSM-16 was molded with 0.6 g of pressurization and supplied to the catalytic conversion of 1,2-propandiol at 673 K, this system resulted in a 94.8% conversion of 1,2-propandiol and 90.5% selectivity to propanal at 0.25 h on-stream, which was the maximum amount of activity. However, at 4.50 h on-stream, the activity decreased extremely to deactivation 19.9% conversion of 1,2-propandiol and 84.7% selectivity to propanal. In contrast, when FSM-16 molded with wet-treatment (0.15 g) was used for the conversion at 573 K, activity was greatly increased and stable 98.6% conversion of 1,2-propandiol and 56.2% selectivity to propanal at 0.25 h on-stream followed by 91.9% and 52.5%, respectively, at 4.50 h on-stream. The hexagonal structure of FSM-16 was suggested to have contributed to the suitable conversion of 1,2-propandiol to propanal

Acidic Properties of Various Silica Catalysts Doped with Chromium for the Oxidative Dehydrogenation of Isobutane to Isobutene

Although previous researchers have found that FSM-16 (#16 Folded Sheet Mesoporous material) doped with chromium and related Cr-doped silica catalysts has shown great activity for the oxidative dehydrogenation of isobutane to isobutene, information on the nature of these catalysts is insufficient. For this study, three types of Cr-doped silica catalysts were prepared by applying the template ion exchange method. CrOx/FSM-16 and CrOx/SiO2 were used as references. These catalysts were used for oxidative dehydrogenation, which was then characterized via various techniques. The most active catalyst was Cr-doped silica, which did not have the hexagonal structure that is characteristic of mesoporous FSM-16. Various characterizations showed that the catalytic activity of the Cr-species, stemmed from a weak acidic nature and a redox nature that originated from the combination of silicate and a Cr cation, as opposed to the hexagonal structure and strong acidic nature of FSM-16

Effects of Acidic Properties of FSM-16 on the Catalytic Conversion of 1,2-Propandiol in the Presence and Absence of Hydrogen

We have earlier showed how the catalytic conversion of 1,2-propandiol to propanal using FSM-16 (#16 folded sheets of mesoporous materials) when molded by wet treatment proceeded more favorably than when using FSM-16 molded by pressurization, while no comparison using other typical acidic catalysts and no examination of the acidic properties of FSM-16 was carried out. In the present study, the conversion using FSM-16 molded by wet treatment and pressurization was compared with that obtained by using typical acidic catalysts such as SiW12O40/SiO2 and MCM-41 (#41 of Mobil Composition of Matter) together with amorphous SiO2. Among these catalysts, FSM-16 molded by wet treatment showed the most suitable catalytic activity. In order to examine the effect of the molding procedure for FSM-16 on its structural and acidic properties, FSM-16 molded by both methods was examined using NH3-TPD, in situ FT-IR using NH3 as a probe molecule, and Hammett indicators together with XRD and TEM. According to Zaitsev's rule, the present conversion should afford acetone rather than propanal, which indicates that it would proceed via hydro cracking. Therefore, the conversion of 1,2-propandiol using FSM-16 was also examined in the presence and absence of hydrogen. Furthermore, hydration reactions of 1- and 2-propanol when using FMS-16 were examined. Based on the results obtained from this investigation, it was concluded that the conversion using a more acidic FSM-16 molded by wet treatment proceeded through dehydration rather than through hydro cracking

The Oxidative Esterification of Propionaldehyde to Methyl Propionate in the Liquid-Phase Using a Heterogeneous Palladium Catalyst

The optimization of the oxidative esterification of propionaldehyde to methyl propionate using a supported palladium catalyst in methanol under heavy-metal-free and pressurized-oxygen conditions, which we recently reported in a previous paper, were carried out together with a study of the reaction route, the nature of the catalytic active sites, and the effect of the support. In our previous paper, we reported significantly improved activity for oxidative esterification using commercially available 5%Pd/Al2O3 at 1.5 MPa of O2 gas and 333 K and emphasized that the doping of 5%Pd/Al2O3 with lead was not needed for the reaction system, but we could not improve the activity that was reported when using 5%Pd/γ-Al2O3 doped with 5% Pb (a 93.2% conversion of propionaldehyde, 76.8% selectivity for methyl propionate and a 71.6% yield of methyl propionate) at 0.3 MPa of O2 gas and 353 K, as reported by another laboratory. In the present study, however, we exceeded those values and obtained a 98.3% conversion of propionaldehyde, 75.3% selectivity for methyl propionate and a 74.0% yield of methyl propionate using 5%Pd/γ-Al2O3 undoped with Pb at 1.5 MPa of O2 gas and 333 K. It should be noted that, in the preparation of the present 5%Pd/γ-Al2O3, Pd was doped onto Al2O3 that had been previously treated with aqueous NaOH. Another active alumina support,η-Al2O3, prepared from boehmite, afforded activity that was substantially lower than that of γ-Al2O3 and depended on the calcination temperature of boehmite to η-Al2O3. When using various concentrations of CH3OH in the aqueous reaction solution, the oxidative esterification proceeded through the formation of propionic acid. To determine why the Al2O3 support afforded better activity than the active carbon support, Pd/Al2O3 and Pd/C catalysts were examined by XAFS (X-ray absorption fine structure). XAFS revealed that Pd on Al2O3 shows a better redox nature than Pd on C, which resulted in activity on Pd/Al2O3 that was better than that on Pd/C

Front Matter

The carbohydrate Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal) is produced in all mammals except for humans, apes and old world monkeys that lost the ability to synthetize this carbohydrate. Therefore, humans can produce high antibody titers against α-Gal. Anti-α-Gal IgE antibodies have been associated with tick-induced allergy (i.e. α-Gal syndrome) and anti-α-Gal IgG/IgM antibodies may be involved in protection against malaria, leishmaniasis and Chagas disease. The α-Gal on tick salivary proteins plays an important role in the etiology of the α-Gal syndrome. However, whether ticks are able to produce endogenous α-Gal remains currently unknown. In this study, the Ixodes scapularis genome was searched for galactosyltransferases and three genes were identified as potentially involved in the synthesis of α-Gal. Heterologous gene expression in α-Gal-negative cells and gene knockdown in ticks confirmed that these genes were involved in α-Gal synthesis and are essential for tick feeding. Furthermore, these genes were shown to play an important role in tick-pathogen interactions. Results suggested that tick cells increased α-Gal levels in response to Anaplasma phagocytophilum infection to control bacterial infection. These results provided the molecular basis of endogenous α-Gal production in ticks and suggested that tick galactosyltransferases are involved in vector development, tick-pathogen interactions and possibly the etiology of α-Gal syndrome in humans.This research was supported by the Consejería de Educación, Cultura y Deportes, JCCM, Spain, project CCM17-PIC-036 (SBPLY/17/180501/000185). JJV was supported by Project FIT (Pharmacology, Immunotherapy, nanoToxicology), funded by the European Regional Development Fund.Peer Reviewe