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This article describes the synthesis of methanol by the direct hydrogenation of CO 2 over Cu/ZrO 2 catalyst at different ZrO 2 concentrations (5, 10, 15, 20 and 25 wt.%) in a three-phase phase reactor. The techniques of N 2 adsorption/desorption, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, temperature-programmed desorption by CO 2 , N 2 O chemisorption and inductively coupled plasma optical emission spectrometry were employed for catalyst characterization. At a reaction temperature of 180 °C, pressure of 3.0 MP and 0.020 g/mL of the catalyst, the conversion of CO 2 and the yield of methanol were 10% and 25 g/kg.h, respectively. Surface area of the metallic copper was increased from 8.1 to 9.5 m 2 /g with the presence of ZrO 2 from 5 to 15 wt.%. The methanol turnover frequency exhibited a linear relationship with ZrO 2 concentration. Methanol synthesis rate was progressively increased with increasing fraction of dispersed copper. A comparative study with the literature revealed better activity of this novel catalyst at relatively low reaction conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] Due to the complexity of the structure–activity relationship of the CuAl 2 O 4 spinel catalyst, optimization of the catalyst structure is a great challenge. In this paper, three different CuAl 2 O 4 spinel catalysts were prepared by the solid-phase method using copper hydroxide, copper nitrate, and copper oxide as the copper source, respectively, to study the difference in the structure of CuAl 2 O 4 spinel catalysts induced by the raw materials and the catalytic behavior for CO hydrogenation. The structure of CuAl 2 O 4 spinel catalyst was characterized by XRD, BET, SEM, TEM, H 2 -TPR and XPS. The activity of CO hydrogenation over the CuAl 2 O 4 spinel catalyst without pre-reduction was evaluated in the slurry reactor. The results demonstrated that different copper sources had obvious influence on the CuAl 2 O 4 spinel texture properties, surface enrichment degree, as well as decomposition and reduction ability, which further regulated the ratio of Cu+/Cu0 and thus affected the catalytic performance, especially the alcohol distribution. The CuAl 2 O 4 spinel, employing copper hydroxide as the copper source, showed better selectivity of C 2+ OH, which was assigned to a higher ratio of Cu+/Cu0, along with larger pore size and pore volume. Moreover, the synergistic effect between Cu0 and γ-Al 2 O 3 improved the selectivity of dimethyl ether. [ABSTRACT FROM AUTHOR]

A series of Cu/ZnO/Al 2 O 3 /ZrO 2 micro-spherical catalysts with different weight percentages of alumina sol from 0 to 20 wt.% are prepared by spray drying method. The as-obtained catalysts are first tested in the fixed-bed reactor for CO 2 hydrogenation to methanol. When the added alumina sol is below 10 wt.%, the CO 2 conversion is close to the equilibrium conversion of CO 2 (26.5%) at 523 K and 5 MPa. Further increase of alumina sol content decreases the activity due to the decreased Cu surface area and weakened interaction among Cu and ZnO. When used in slurry bed, attrition resistance of catalysts plays an important role to determine the final catalytic performance. The catalyst without addition of alumina sol possesses low attrition resistance, which leads to catalyst loss and deactivation during reaction process. The introduction of suitable amount of alumina sol can enhance the attrition resistance of the catalysts markedly, and the catalytic activity can be still maintained at a high value. The spray-dried Cu/ZnO/Al 2 O 3 /ZrO 2 catalyst with addition of 10 wt.% alumina sol exhibits the best performance with high activity and high stability. [ABSTRACT FROM AUTHOR]

crude biosurfactant mixture was produced in a 1.4 L tubular reactor by a mixed culture; after the thermal treatment of the whole culture an increase in emulsification activity and surface tension was observed, with a main effect on the first one. The emulsification index of the mixture obtained was of 60.4 %. The crude mixed biosurfactant was used to enhance hydrocarbon biodegradation of intemperized soil in a slurry reactor, for which two biodegradation assays were carried out. In the first reactor (R1), the crude mixed biosurfactant was added along with inoculum at initial stage, and the second reactor (R2) was inoculated 5 days after the initial biosurfactant addition. When the crude biosurfactant mixture was added as a pretreatment (R2), the extent and rate of hydrocarbon biodegradation was increased efficiently in the slurry phase reactor 1.3-folds in comparison to non-biosurfactant control. So, the initial hydrocarbon content (9,275 g/kg of dry soil) was reduced to 674 ± 34 mg kg-1 with about 92% of removal efficiency at the 10 days of treatment in the slurry reactor. On the other hand, the bioreactor that received the biosurfactant and the inoculum at the initial stage showed slower hydrocarbon consumption and as result hydrocarbon content was reduced by approximately 34%. [ABSTRACT FROM AUTHOR]

The photocatalytic degradation of a textile azo dye in a slurry photoreactor with recirculation of the suspension, by heterogeneous photocatalytic processes, was studied in this paper. A simple kinetic model for variation of the photodegradation rate in time was proposed for the investigated system. Characteristics of the reactor were described and its photocatalytic performances in degradation of the studied textile dye under solar illumination were ascertained. The photodegradation of the organic molecule was demonstrated to follow approximately a pseudo-first kinetic order, according to the Langmuir- Hinshelwood model. Study concerning the effect of light intensity revealed a rate dependence rather of square root of the intensity within the investigated range. [ABSTRACT FROM AUTHOR]