Search

Metal leaching is a major issue in efficient production of γ-valerolactone (GVL) from levulinic acid (LA) under mild reaction conditions. In this study, Ag was added to Cu-supported γ-Al2O3 catalyst to suppress Cu leaching in the hydrogenation of LA into GVL. The CuAg/Al2O3 catalyst was reduced in situ during the reaction, and Cu leaching in the solution was significantly suppressed. The bimetallic catalyst without reduction pretreatment achieved approximately 100% yield to GVL and exhibited good reusability in nine consecutive cycles under mild reaction conditions of 180 °C and 1.4 MPa H2 pressure in tetrahydrofuran (THF). The strong interplay in the geometric and electronic effects between Cu and Ag was verified through XPS, H2-TPR, TEM, STEM/EDS, and XRD analyses. This paper extensively discussed the mechanism of Ag on preventing Cu leaching and the superiority of in situ reduction in solution over external reduction in gas.

The etherification of glycerol with isobutene to synthesize di-tert-butyl glycerol ethers (DTBG) and tri-tert-butyl glycerol ether (TTBG) was studied on acid-treated HY zeolites. Compared to the parent commercial HY, both activity and selectivities to the desired ethers were doubled after optimal acid treatments. At 70 °C with 1 wt% catalyst loading, the glycerol conversion and the selectivities to DTBG and TTBG after 7 h were 85% and 58%, respectively on a citric acid washed HY. The catalyst showed higher selectivity than an acidic resin (SAC-13) and was reusable. Similar performance was also achieved using nitric acid solutions. Although the acid wash resulted in fewer acid sites due to dealumination, the zeolite crystalinity was retained. Besides increased acid strength, enlarged surface area and pore volume from the generation of mesopores were observed, which were likely to be the key factors for the improved catalytic performance by facilitating mass transfer.

Our previous work showed that for catalytic alkylation of m-cresol with tert-butanol (TBA) S0 3 H-functionalized ionic liquids exhibited several characteristic advantages over conventional catalysts. This work investigated the reaction mechanism of the alkylation of m-cresol with tert-butanol catalyzed by the S0 3 H-functionalized ionic liquid (IL) through quantum chemical calculation in combination with the experimental studies. The experimental results showed that 2-tert-butyl-5-methyl phenol (2-TBC), 4-tert-butyl-3-methyl phenol (4-TBC) and tert-butyl-m-cresol ether (TBMCE) products were all primary products, while 2,6-di-tert-butyl-3-methyl phenol (2,6-DTBC) was a secondary product. The calculation results indicated that the selectivities of the products depended on the fundamental natures of the reactive sites, including the orbital overlap, the Coulomb and the steric effect in the interaction between the tert-butyl ion ([t-C 4 H 9 ] + ) and the m-cresol; the TBMCE was dynamically favored but not thermodynamically stable, while the C-alkylated products, especially 2-TBC, were the thermodynamically preferred products; the IL played an important role in generating the [t-C 4 H 9 ] + from the TBA and the final products from the intermediates.

Supported Cu catalysts were synthesized and applied to convert glycerol, a renewable feedstock, to value-added propanediols. Among these catalysts, the γ-Al 2 O 3 supported Cu catalysts showed superior performance. Unlike most supported precious metal catalysts, the scission of C–C bonds was successfully suppressed on the Cu/Al 2 O 3 catalysts without a sacrifice of glycerol conversion. The experimental results combined with the characterization studies using temperature programmed reduction (TPD) and X-ray diffraction (XRD) techniques revealed that the optimal Cu loading was 2.7 mmol of Cu metal/g of γ-Al 2 O 3 and that the suitable pre-reduction temperature was 300 °C. The Cu/Al 2 O 3 catalyst with the optimized amount of Cu showed a selectivity to propanediols about 96.8% with a glycerol conversion about 49.6% under mild reaction conditions (220 °C, 1.5 MPa initial H 2 pressure, 10 h, Cu/glycerol molar ratio 3:100). Compared with a commonly used commercial copper chromite catalyst, the Cu/Al 2 O 3 presented much higher activity, selectivity and Cu usage efficiency and is non-toxic.

Background Schistosoma japonicum is the most widespread schistosoma in the world. Although gastrointestinal system involvement with S japonicum appears to be considerably common, cerebral schistosomiasis is not frequent. Cerebral schistosomiasis japonica intestinal and hepatosplenic involvement is more rare. We collected 2 cases of cerebral schistosomiasis identified by pathological diagnosis, lacking extracranial involvement. In addition, one of them had multiple lesions, which was also rare. Case Description Two male patients came from Dongting Lake region, Hunan province, one of the oldest and most severe endemic areas of China. Their clinical symptoms varied, such as headache, dizziness, seizures, and others. Studies in blood were normal except for eosinophilia. Computed tomography of brains showed hyperdense areas, and MRI showed isointense signal on T1-weighted images, hyperintense signal on T2-weighted images, and heterogeneous enhancement. The definitive diagnosis was cerebral schistosomiasis japonium by biopsy. Standard use of praziquantel and corticosteroid drugs was applied, and the prognosis was good. Conclusion Cerebral schistosomiasis japonica without intestinal and hepatosplenic involvement is exactly rare and easily ignored. The diagnosis sometimes is difficult. Laboratory and imaging examinations are helpful but not specific. Although operation can give the definitive diagnosis, it is not imperative. The administration of praziquantel and corticosteroid drugs in early stages is good for prognosis.

A commercial Beta-type zeolite was studied for upgrading unsaturated fatty acids, a renewable feedstock. Catalyst calcination and additive addition were investigated aiming to improve the catalytic activity for the skeletal isomerization of oleic acid. Calcination at a temperature around 450 °C instead of the commonly used 550 °C generated catalysts with relatively low surface areas but high activities, which is attributed to the high Bronsted acidity as revealed by FTIR characterization. Addition of a small amount of water (2–5 wt% of fatty acid) to the fatty acid promoted the conversion, but any further increase in the amount of water would result in a catalytic activity loss. Although methanol did not show a promoting effect for the isomerization, the methyl ester of oleic acid showed a higher conversion than oleic acid on the same catalyst. The poisoning effect of the carboxylic group on oleic acid was demonstrated by the comparison of the isomerization reactions of oleic acid and 1-octadecene.

Activated carbons have been prepared from petroleum cokes by the combination of a chemical treatment with HClO4 or H2O2 and a chemical activation with KOH at a constant KOH/coke ratio of 3/1. The influence of different chemical treatments on the properties of the activated carbon precursors and final carbons activated with KOH was invested by using XRD, FTIR, and BET techniques. XRD results indicated that the value of interplanar distance d002 increased by chemical treatment and the disappearance of the peak corresponding to 0 0 2 faces correlated to high specific surface area. FTIR studies showed that chemical modification promoted the formation of surface oxygen functionalities. Significant effects on BET surface area, pore texture and iodine adsorption capacity were evidenced. The results show that chemical modification prior to activation dramatically increased the BET surface area and total pore volume of the resulting activated carbon. Modified petroleum coke based activated carbon with chemical activation had higher specific surface area (2336 m2/g) and better iodine adsorption value (1998 mg/g).

Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurologic inherited disease with heterogeneity. Autosomal dominant (AD) is the common inherited mode. There have been two loci mapped to 16 chromosome for PKD. However, no gene responsible for it has been identified so far. We collected 6 pedigrees from Chinese mainland. There were 122 members in all, including 26 affected. According to New diagnostic criteria of Bruno, they were diagnosed as pure PKD. From the clinic data, we found that the onset age was earlier and the severity was increasing in the subsequent generations in 4 pedigrees of them, which suggested genetic anticipation. Linkage analysis was applied in 2 of these pedigrees. The maximum LOD score and NPL score were negative. The followed haplotypes analysis excluded the PKD locus in both families from chromosome 16, providing evidence for a novel locus.

The SO 3 H-functionalized ionic liquids were synthesized by using tri-alkylamine and 1,4-butanesultone as the source, and characterized by NMR and TOF-MS, and their catalytic performance for the tert -butylation of m-cresol with tert -butanol (TBA) were investigated. The reaction time, reaction temperature, molar ratio of m-cresol to TBA, and the recycle number of the spent ionic liquid were examined. Under optimum reaction conditions, the conversion of m-cresol and the selectivity to 2- tert -butyl-5-methyl phenol (2-TBC) were 81% and 96%, respectively. No apparent loss of activity and selectivity of the ionic liquid were observed after four recycles. The acidity of ionic liquids determined by Hammett method is about the same as that of conventional acid, such as H 2 SO 4 . The possible mechanism for this reaction system was discussed based on the reaction results and the ab initio calculation results.