研究了五氟乙烷生产过程中催化剂三正丁胺的失活与再生行为,分别探讨了上、中、下3层失活催化剂的失活机理,针对失活机理不同的失活催化剂采用了不同的再生方法.结果表明:上层失活催化剂的失活形态主要为三正丁胺、HF与四氟乙烯的络合物,采用先在氮气氛围加热分解络合物再减压精馏的方式再生,三正丁胺的收率达83.8％;中层失活催化剂的失活形态主要为络合物与四氟乙烯的低聚物,采用失活催化剂与CaCl2水溶液反应再加碱分相的方式再生,三正丁胺的收率达69.4％;下层失活催化剂的失活形态主要为聚合物、二正丁胺和季铵盐,不再具有回收价值.

ZnO-TiO2 sorbents synthesized by an impregnation method were characterized through XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy) and EDS (Energy dispersive spectrometer) analyses. An experiment concerning the adsorption of Hg0 by ZnO-TiO2 under a simulated fuel gas atmosphere was then conducted in a bench-scale fixed-bed reactor. The effects of ZnO loading amounts and reaction temperatures on Hg0 removal performance were analyzed. The results showed that ZnO-TiO2 sorbents exhibited excellent Hg0 removal capacity in the presence of H2S at 150 °C and 200 °C; 95.2% and 91.2% of Hg0 was removed, respectively, under the experimental conditions. There are two possible causes for the H2S reacting on the surface of ZnO-TiO2: (1) H2S directly reacted with ZnO to form ZnS, (2) H2S was oxidized to elemental sulfur (S ad ) by means of active oxygen on the sorbent surface, and then S ad provided active absorption sites for Hg0 to form HgS. This study identifies three reasons why higher temperatures limit mercury removal. First, the reaction between Hg0 and H2S is inhibited at high temperatures. Second, HgS, as the resulting product in the reaction of mercury removal, becomes unstable at high temperatures. Third, the desulfurization reaction strengthens at higher temperatures, and it is likely that H2S directly reacts with ZnO, thus decreasing the S ad on the sorbent surfaces.

CeTi sorbent (CeO2 supported on TiO2) was employed to remove elemental mercury (Hg-0) from syngas when H2S and/or HCl are present. CeTi sorbents exhibited higher Hg-0 removal efficiency compared with S-impregnated activated carbon. H2S and HCl were the most effective syngas components responsible for Hg-0 removal when they were employed separately. When 400 ppm H2S and 10 ppm HCl were introduced separately with a balance of dry N-2, over 97% of the Hg-0 was removed under the experimental conditions. However, the combination of H2S and HCl exerted a prohibitive effect on Hg-0 removal, which could be attributed to two causes: (1) the HCl consumed the surface oxygen active for Hg-0 removal, hence limiting Hg-0 removal by H2S; and (2) the H2S competed with Hg-0 for active adsorption sites, limiting the Hg-0 removal by HCl. On the basis of the temperature-programmed decomposition (TPD) analysis and X-ray photoelectron spectroscopy (XPS) characterization of the sorbents, a Hg-0 removal mechanism in the presence of H2S over CeTi sorbents was proposed, suggesting that surface oxygen on the of CeTi sorbent supported the transformation of H2S to active surface sulfur, through which Hg-0 could be captured resulting in the formation of HgS. (C) 2013 Elsevier B.V. All rights reserved.

A series of CeO2-TiO2 (CeTi) sorbents with different CeO2/TiO2 mass ratios were prepared by an impregnation method and employed to remove elemental mercury (Hg(0)) in simulated syngas. The CeTi sorbents with a CeO2/TiO2 mass ratio of 0.2 exhibited superior Hg(0) removal efficiency from 80 to 150 °C, which could be ascribed to the greater amount of surface chemisorbed oxygen resulted from Ce(3+) on the sample surface. H2S was the most effective syngas component responsible for Hg(0) removal. The use of 400 ppm H2S resulted in 98% Hg(0) removal efficiency under the experimental conditions. H2 and CO had a negligible effect on the efficiency of Hg removal. In the presence of H2S, a prohibitive effect of HCl and NH3 on Hg(0) removal was observed because of the consumption of the surface oxygen. Water vapor also inhibited Hg(0) removal due to competitive adsorption with H2S. Hg(0) removal over CeTi sorbents was proposed to follow the Eley-Rideal mechanism, in which active surface sulfur reacts with gas-phase Hg(0). This large oxygen storage capacity of CeTi sorbents is quite favorable to H2S catalytic oxidation and Hg(0) emission control in an extremely reducing environment, such as when there is a deficiency of O2.

The adsorption of gas-phase elemental mercury by iron oxide sorbent under nitrogen and simulated gas atmosphere was studied on a bench-scale fixed-bed apparatus by using mercury online analyzer.The result showed that,the calcination of the iron oxide sorbent suppressed the removal of the mercury under N2 atmosphere.The iron oxide sorbent had a high mercury removal efficiency under H2S atmosphere and the mercury removal efficiency can be maintained above 90% for a long time.The elemental mercury removal efficiency was influenced strongly by the adsorption temperature.With the adsorption temperature increased,the elemental mercury removal efficiency varied in the shape of a mountain.

The adsorption of gas-phase elemental mercury by iron oxide adsorbent synthesized by an ultrasonic-assisted precipitation method under nitrogen and simulated gas atmosphere was studied on a bench-scale fixed-bed apparatus by using mercury online analyzer. And the effect of various gases on Hg0 removal performance by iron oxide adsorbent was analyzed. The result showed that the mercury removal efficiency of iron oxide adsorbent is low under N2 atmosphere. H2S promotes the Hg0 removal by iron oxide adsorbent. The iron oxide adsorbent has a high mercury removal efficiency under H2S atmosphere and the mercury removal efficiency can be maintained above 90%for a long time. The effects of CO and H2 were not observed at 150,℃. H2O suppressed the mercury removal at 150,℃. With the increase of adsorption temperature,the elemental mercury removal efficiency increases first and then gradually de-creases.

Nano-ZnO sorbents synthesized by a homogeneous precipitation method were characterized by BET (Brunauer-Emmett-Teller), XRD (X-ray diffraction) as well as XPS (X-ray photoelectron spectroscopy) analysis. The adsorption of elemental mercury by nano-ZnO under nitrogen and simulated gas atmosphere was studied on a bench-scale fixed-bed apparatus. The effect of various gases on Hg0 removal performance by nano-ZnO was analyzed. The results show that the mercury removal efficiency of the nano-ZnO is relatively poor in nitrogen atmosphere. The presence of H2S promotes the Hg0 removal by nano-ZnO observably and the mercury removal efficiency can be maintained for a long time even after stopping pass into H2S. The presence of CO and H2 promote the Hg0 removal by promotion of nano-ZnO desulfurization. As the temperature increases, the formation of elemental sulfur in the surface of the nano-ZnO gradually reduces, leading to suppress the removal of Hg0.

In this study,HPLC was used to detect the podophyllotoxin content in three parts of Dysosma versipellis(Hance).The content was 0.60% in the wild root,while in the calli and the induced root from this calli,they were 0.117% and 0.148%,respectively.The results suggest that it is possible to produce podophyllotoxin quickly by tissue culture,and provide much raw material to antitumor drugs with little damage to the natural resources.