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Propane dehydrogenation in oxygen free environment over alumina-supported chromium oxide catalysts with different chromium loading was studied within short time-on-stream range for the fluidized moving bed applications. For this purpose, a series of CrOx/Al2O3 and CrOx/Zr-Al2O3 catalysts were prepared and examined. Increase in the chromium loading resulted in reduction of monochromate species, possibly leading to formation of polychromate species. Further increase of chromium loading led to formation of Cr2O3 species. Accordingly, specific activity of the catalyst decreased with increasing chromium loading. Propane conversion significantly decreased and propylene selectivity increased during an induction period due to the rapid consumption of limited lattice oxygen in the catalyst. Equilibrated and artificially-aged catalysts were characterized in order to investigate the factors affecting propylene selectivity and catalyst durability by pore analysis, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (NH3-TPD), X-ray diffraction patterns (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). After an artificial catalyst aging treatment, all catalysts showed reduction in catalytic activity and the most drastic activity decrease was found in the catalyst with the highest loading of 20 wt% Cr/γ-Al2O3 sample. The activity loss was mainly due to agglomeration of the chromium species, reduction of the surface area, and transformation of Cr6+ species into stable Cr2O3 species. Cr species were agglomerated on the surface of alumina support during the aging treatment and the agglomeration was more pronounced at the high Cr loading. Moreover, Raman spectroscopy and XRD analyses revealed the formation of chromia/alumina solid solution in the catalyst after the aging treatment which also significantly contributed to the activity loss. Contrarily, Zr modified alumina support successfully suppressed the formation of chromia/alumina solid solution phase and substantially improved the catalytic activity after the aging treatment by increasing the dispersion of chromium oxide. Zr-Al2O3 support showed lower catalytic activity toward propylene than Al2O3 support, which also contributed to the higher propylene yield of Cr/Zr-Al2O3.

A multi-stage fluidized bed process for CO 2 capture is a novel process for reducing regeneration energy. This process is consist of low-, mid-, and high-temperature stage. Each stage has an absorber and a regenerator. Solid absorbents circulating in these fluidized beds absorb and regenerate CO 2 by temperature swing. PEI-, MgO-, and Li 4 SiO 4 -based absorbents are utilized for low-, mid-, and high-temperature stage. The main feature of this process is a heat recovery scheme; i) an intra-stage heat exchanger, ii) an inter-stage heat exchanger. In the intra-stage heat exchanger, a sensible heat of lean and rich sorbents from regenerator and absorber is exchanged. In the inter-stage heat exchanger, a heat of absorption of mid- and high-temperature stage is supplied to a heat of regeneration of low- and mid-temperature stage. A bench-scale facility that can process 60 Nm 3 /hr flue gas is constructed for conducting a feasibility study of this process. From the experiments of the low-temperature stage, it can capture CO 2 with an efficiency of 80%, however, due to a low efficiency of intra-stage heat exchanger, the regeneration energy and total utility cost are estimated as 4.65 GJ and $36.9 per ton-CO 2 . The three-stage process is evaluated through a process simulation study based on the absorption performance measured at a lab-scale apparatus. The resulted regeneration energy is estimated as 2.37 GJ per ton CO 2 and total utility cost is $39.1 and $24.5 per ton CO 2 in the absence and in the present of steam-turbine, respectively. Finally, a parametric study of the absorption capacity of sorbents and MTA of intra-stage heat exchanger are also been conducted and discussed.

CuO/Al 2 O 3 was used for dehydrogenation of butenes (1-butene, cis-2-butene, and trans-2-butene) to 1,3-butadiene at 200 °C under an anaerobic condition without an excessive amount of dilution. 1,3-butadiene was selectively obtained from butenes without the formation of carbon oxides over the CuO/Al 2 O 3 catalyst. Bifunctionality of oxidation and C−H bond activation by CuO and Al 2 O 3 , respectively, were strongly required for the selective conversion of the butenes to 1,3-butadiene.

The inter-conversion of light olefins over four types of HZSM-5 based catalysts under cracking conditions was investigated systematically and various methods including XRD, Ar adsorption–desorption, NH3-TPD, 27Al and 31P MAS–NMR were used to characterize the effects of P modification and steaming on ZSM-5. Regardless the types of catalyst, the same behaviors of light olefin inter-conversion were observed only depending on conversion of light olefins. Also, the conversion and selectivity were not influenced by the presence of hydrogen, suggesting that light paraffins were mainly produced from hydrogen transfer during cracking rather than hydrogenation of light olefins. It can be suggested that the inter-conversion of light olefins occurs through oligomerization of light olefins and then re-cracking of the oligomerized products. To guarantee high light olefin yield in catalytic naphtha cracking, it is strongly required to suppress oligomerization of light olefins during catalytic cracking.

Hydrogenation of silicon tetrachloride (SiCl 4 ) to trichlorosilane (SiHCl 3 ) using carbon-based catalysts is studied. The results show that surface functional groups that result from the defect sites of the carbon catalysts play an important role in producing SiHCl 3 . Because the metal−carbon composites obtained by treating sucrose and transition metals at high temperature in the N 2 flow have more defect sites, they display an increased SiHCl 3 yield. Elemental analysis of the catalyst and reaction results demonstrate that there is a very good correlation between the SiHCl 3 yield and the amount of deposited silicon during the induction time, and the SiHCl 3 yield and the accumulated amount of deposited Si species rapidly change initially and then reach a stable value. Hydrogenation of SiCl 4 to SiHCl 3 in metal-grade silicon (mg−Si) powder is known to give a higher equilibrium conversion of SiCl 4 . In a similar way, by introducing Si powder into the catalyst bed, a higher SiHCl 3 yield can be obtained. It is important to retard the reverse reaction rate of HCl and SiHCl 3 to increase the SiHCl 3 yield; therefore, the HCl concentration in the product stream should be reduced as soon as it is formed on the catalyst surface during the hydrogenation of SiCl 4 . Consequently, the Si-doped metal−carbon composite catalyst shows a higher SiHCl 3 yield than that of the physically-mixed catalyst and mg−Si powder. These results offer a quite promising potential for developing a stable and effective SiCl 4 hydrogenation catalyst and can promote a deeper understanding of this important poly-Si industry reaction.

Cytokinin signaling in Arabidopsis thaliana utilizes a multi-step two-component signaling (TCS) system comprised of sensor histidine kinases (AHKs), histidine phosphotransfer proteins (AHPs), and response regulators (ARRs). Recent studies have suggested that the cytokinin TCS system is involved in a variety of other signaling and metabolic pathways. To further explore a potential function of the cytokinin TCS in the Arabidopsis dehydration stress response, we investigated the expression of all type-A ARR genes and a type-C ARR, ARR22, in both wild type and ahk single, double, and triple mutants in response to dehydration compared to cytokinin as well as dehydration tolerance of ahk mutants. We found that drought significantly induced the expression of a subset of ARR genes, ARR5, ARR7, ARR15, and ARR22. The results of expression analyses in ahk single, double, and triple mutants demonstrated that the cytokinin receptors AHK2 and AHK3 are redundantly involved in dehydration-inducible expression of ARR7, but not that of ARR5, ARR15, or ARR22. Dehydration tolerance assays showed that ahk2 and ahk3 single mutants exhibited enhanced dehydration tolerance compared with that of wild-type plants and ahk4 mutants, and that ahk2 ahk3 double mutants exhibited stronger drought tolerance than that of ahk3 ahk4, which exhibited more enhanced drought tolerance than that of wild-type plants and ahk single mutants. Taken together, these results demonstrate that while the cytokinin receptors AHK2 and AHK3 are critically involved in the dehydration tolerance response, both cytokinin receptor-dependent pathway and receptor-independent pathway occur in the dehydration response regulating ARR gene expression. In addition, preincubating ahk2, ahk3, ahk4, and the wild-type plants with cytokinin induced enhanced dehydration stress tolerance in these plants, demonstrating that cytokinins are involved in regulating plant response to dehydration stress.

The influences of steaming or washing treatment on P-modified HZSM-5 catalyst were investigated systematically in order for getting deep insight into the role of P species in catalytic cracking. The impregnation of P leads to better hydrothermal stability and higher yields of light olefin (ethylene and propylene), but brings rapid decrease of acidity. During steaming, the impregnated P species become more condensed phase and the acidity and catalytic activity decreased further. However, the acidity and catalytic cracking activity recovered just by washing with water even for steamed samples, suggesting that the existence of condensed P species blocks the pores of zeolite reversibly and are responsible for the decrease of cracking activity of naphtha.

Micro-spherical Ni 0.80 Co 0.15 Mn 0.05 (OH) 2 precursors with a narrow size-distribution and high tap-density are prepared successfully by continuous co-precipitation of the corresponding metal salt solutions using NaOH and NH 4 OH as precipitation and complexing agents. LiNi 0.80 Co 0.15 Mn 0.05 O 2 is then prepared as a lithium battery cathode from this precursor by the introduction of LiOH·H 2 O. The pH and NH 3 :metal molar ratio show significant effects on the morphology, microstructure and tap-density of the prepared Ni 0.80 Co 0.15 Mn 0.05 (OH) 2 and the R values and I (0 0 3)/ I (1 0 4) ratio of lithiated LiNi 0.80 Co 0.15 Mn 0.05 O 2 . Spherical LiNi 0.80 Co 0.15 Mn 0.05 O 2 prepared under optimum conditions reveals a hexagonally ordered, layered structure without cation mixing and an initial charging capacity of 176 mAhg −1 . More than 91% of the capacity is retained after 40 cycles at the 1 C rate in a cut-off voltage range of 4.3–3.0 V.

ZSM-5 was synthesized by template-free method using sodium silicate as a silica source and the content of Na2O in mother liquid was controlled by H2SO4. To see the effect of Na2SO4 generated by added H2SO4, hydrothermal crystallization was carried out with two types of mother liquids having low and high Na2SO4 contents at 170 C. The physical and chemical properties of ZSM-5s prepared in two different con- ditions were compared by XRD, EDS, FTIR, micropore analyzer and particle size analyzer. High crystalline, isometrical shaped and uniform 1-2 lm sized ZSM-5s with relative crystallinity around 100% could be obtained successfully from the mother liquids having the molar range of (11.0-21.0) Na2O:(21.4-11.4) Na2SO4:100.0 SiO2:2.0 Al2O3:4000.0 H2O. Through the crystallization in the absence and presence of extra Na2SO4, it was found that the condensation rate of aluminosilicate was increased by the Na2SO4 and resulted in the formation of amorphous phase instead of crystalline ZSM-5. The formation of crystalline HZSM-5 was prohibited critically if the total amount of Na2SO4 in mother liquid was higher than 24.4 mole based on 100.0 mole of SiO2. The enhanced condensation reaction and the preferential formation of agglomerated amorphous aluminosilicates in the presence of Na2SO4 could be explained by the oxy- anion effect of SO 2� 4 generated by Na2SO4.

Selective production of 2,6-dimethylnaphthalene (2,6-DMN) from 2,7-rich DMN has been investigated, with one-step and successive three-step isomerization containing (i) hydrogenation of 2,7-rich DMN to 2,7-rich dimethyl tetralin, (ii) isomerization of 2,7-rich DMT to 2,6-rich DMT, and (iii) dehydrogenation of 2,6-rich DMT into 2,6-rich DMN, respectively. It was found that the intra-triad isomerization of DMN was possible even at 200 °C, but for the inter-triad isomerization at least 250 °C was required. If the reaction temperature is higher than 300 °C, the yield of 2,6-DMN decreases rapidly due to the side reactions such as dealkylation, cracking and transalkylation. It was also found that 2,6-DMN or 2,6-DMT selectivity were strongly dependant on the Si/Al ratio of H-BEA (or the Bronsted site) and the maximum yield of 2,6-DMN (or 2,6-DMT) was obtained at the Si/Al ratio of 12.5. In the case of DMT, inter- and intra-triads did not show difference in isomerization temperature and were possible even at 180 °C. 14.9% yield of 2,6-DMT was obtained through the three-step isomerization over H-BEA(12.5) at 200 °C, while 10% yield of 2,6-DMN was achieved by one-step isomerization over H-BEA(12.5) at 250 °C.