The mechanism and kinetics of methyl isobutyl ketone synthesis from acetone over ion-exchanged hydroxyapatite

The synthesis of methyl isobutyl ketone (MIBK) can be carried out by the condensation of acetone in the presence of hydrogen over a supported metal catalyst. Previous studies have shown that hydroxyapatite is an excellent catalyst for condensation reactions. The present investigation was undertaken in order to elucidate the reaction mechanism and site requirements for acetone coupling to MIBK over a physical mixture of hydroxyapatite and Pd/SiO2. The reaction is found to proceed by consecutive aldol addition to form diacetone alcohol (DAA), dehydration of DAA to mesityl oxide (MO), and hydrogenation of MO to MIBK. The products formed by feeding DAA and MO reveal that aldol addition of acetone is rapid and reversible, and that the subsequent dehydration of DAA is rate-limiting. Pyridine and CO2 titration show that aldol dehydration occurs over basic sites via an E1cB mechanism. A series of cation-substituted hydroxyapatite samples were prepared by ion-exchange to further investigate the role of acid-base strength on catalyst performance. Characterization of these samples by PXRD, BET, ICP-OES, XPS, CO2-TPD, and Raman spectroscopy demonstrated that the exchange procedure used does not affect the bulk properties of hydroxyapatite. DFT calculations reveal that in addition to affecting the Lewis acidity/basicity of the support, the size of the cation plays a significant role in the chemistry: cations that are too large (Ba2+) or too small (Mg2+) adversely affect reaction rates due to excessive stabilization of intermediate species. Strontium-exchanged hydroxyapatite was found to be the most active catalyst because it promoted α-hydrogen abstraction and C–O bond cleavage of DAA efficiently

Cu and Fe oxides dispersed on SBA-15:a Fenton type bimetallic catalyst for N,N-diethyl-p-phenyl diamine degradation

A bimetallic oxidation catalyst has been synthesized via wet impregnation of copper and iron over a mesoporous SBA-15 silica support. Physicochemical properties of the resulting material were characterized by XRD, N2 physisorption, DRUVS, FTIR, Raman, SEM and HRTEM, revealing the structural integrity of the parent SBA-15, and presence of highly dispersed Cu and Fe species present as CuO and Fe2O3. The CuFe/SBA-15 bimetallic catalyst was subsequently utilized for the oxidative degradation of N,N-diethyl-p-phenyl diamine (DPD) employing a H2O2 oxidant in aqueous solution

Analysis of Business Strategies of Xiaomi

The Smartphone manufacturer from China has a very novel business model wherein they manufacture cell phones in batches thereby keeping the inventory costs on a very low side. The company has really challenged the brick and mortar model and sell online, thereby cutting down the intermediaries and keeping the costs down for the company. The company sells smartphones almost on the cost price. The profit margin is very thin, and the company believes that they will make money by selling accessories and other complementary things. The problem which ascends now is that how Xiaomi would be able to adjust to the increased competition from other players like Huawei and ZUK from Lenovo who have imitated the same model. The second issue which has come to time light is that would this business model be sustainable over the long period. The third issue is how the company would react to the decline in the smartphone sales in China which has been one the main driving forces responsible for companies growth

Induction of cell-specific apoptosis and protection from Dalton's lymphoma challenge in mice by an active fraction from Emilia sonchifolia

Objective: To isolate an active anticancer fraction from Emilia sonchifolia   and to determine the mechanism of its anticancer activity. Materials and methods: The anticancer principle was separated using thin layer chromatography (TLC) from the most active n-hexane extract and chemically analysed. The anticancer efficacy of n-hexane extract was determined in mice using Dalton′s lymphoma ascitic (DLA) cells. Cytotoxicity of the extracts and isolates to macrophages, thymocytes and DLA cells was measured using Trypan blue exclusion method, MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay, DNA ladder assay and DNA synthesis in culture. Short-term toxicity evaluation of the active fraction was also carried out in mice. Results: The hexane extract was found to be most active and it showed in vitro cytotoxicity to DLA and thymocytes, but not to macrophages. In a concentration and time-dependent manner, it induced membrane blebbing, nuclear condensation, DNA ladder formation, and formation of apoptotic bodies which are characteristic to apoptotic cell death. The n-hexane fraction protected 50% of mice challenged intraperitoneally with 106 DLA cells. This fraction did not exhibit conspicuous adverse toxic symptoms in mice. An active terpene fraction was separated from the n-hexane extract by TLC. This isolate induced apoptotic cell death in DLA cells at 0.8 µg per mL level. Conclusion: An anticancer terpene fraction was isolated by TLC from Emilia sonchifolia that induced cell-specific apoptosis and appears to be a promising anticancer agent

Propene oligomerization using Alkali metal- and nickel-exchanged mesoporous aluminosilicate catalysts

A series of alkali metal- and nickel-exchanged Al-MCM-41 catalysts were prepared via aqueous ion exchange and then investigated for gas-phase oligomerization of propene at 453 K and near ambient pressures. All catalysts were active and produced oligomers with >98% selectivity. The highest activities per Ni2+ cation were observed when the cations were highly dispersed as a consequence of either lowering the Ni loading for a fixed MCM-41 Si/Al ratio or by decreasing the concentration of exchangeable sites within the material by increasing the MCM-41 Si/Al ratio at a fixed Ni loading. The identity of the alkali metal cation had no significant effect on the catalytic activity or degree of dimer branching, except for the sample containing Cs + cations, where the decreased pore volume resulted in a lower catalyst activity and slightly more linear dimer products. Comparison of Ni-MCM-41 prepared with and without Na+ cations showed that a higher yield of oligomers could be achieved when Na+ cations are present because of partial removal of strong Brønsted acid sites. For the same reaction conditions, Ni-Na-MCM-41 was more than twice as active as smaller-pored Ni-Na-X zeolites, demonstrating that the activity of Ni2+ cations increases with the increasing free volume near the site. This effect of free volume on the activity of Ni2+ cations was further confirmed by comparing the activities of Ni-Na-X, Ni-Na-MCM-41, Ni-Na-MCM-48, and Ni-Na-SBA-15 with respect to pore size. © 2013 American Chemical Society

Information Technology Innovations in Library Management: A Case of SIMS

Academic libraries are facing a piquant situation and unforeseen challenges in this age of information technology. They are reeling under pressure to fulfill their obligation of meeting the diverse information needs of their stakeholders. The rapid implementation of information technology in all areas of life, including libraries, has led to concerns about how information technology transforms the nature and quality of work. What is the impact of information technology on simplifying the service functions?. Library, office, and industrial automation research have shown that the impact of technology depends on how and why it is used, rather than on the technology itself. Library management systems are commonly used in all educational related institutes. Many commercial products are available. However, many institutions may not be able to afford the cost of using commercial products or may not get satisfaction in customization facilities available. Alternatively, the institution itself can take a decision to develop its library management system software using its own expertise. Library management system is a modern innovation that is expected to help in the circulation registration of processed books and register users. A case study is undertaken at SIMS library to know the effect of automation on the quality of providing library services, user satisfaction of library services, the effective automation of work, and the control of library functions. This paper discusses the impact of the automated system on staff, job satisfaction, and client relations. Results showed that the developed system made a significant impact on the quality library service management

Hydrogenation of butanal over silica-supported Shvo's catalyst and its use for the gas-phase conversion of propene to butanol via tandem hydroformylation and hydrogenation

The objective of the present study was to develop a heterogeneous catalyst for the hydrogenation of butanal that could function in the presence of CO and propene and, hence, could be used in a tandem reactor to enable the gas-phase conversion of propene and synthesis gas to butanol. To this end, we investigated the activity of silica-supported Shvo's catalyst (Shvo/SiO2) for the gas-phase hydrogenation of butanal. Experiments were performed to determine the kinetics of n- and iso-butanal hydrogenation. The apparent activation energies and the apparent partial pressure dependencies of n- and iso-butanal, H 2, and CO on the rates of n- and iso-butanol formation were determined. A mechanism for butanal hydrogenation was proposed to rationalize the observed kinetics and some of the reaction intermediates were observed by in situ infrared and 31P MAS NMR spectroscopy. It was found that Shvo/SiO2 was inhibited by SX (SX = sulfoxanthphos) and CO, and is inactive for alkene hydrogenation. The tandem catalytic conversion of propene and synthesis gas to butanol was then carried out using a SX-Rh supported ionic liquid phase (SILP) catalyst to promote the hydroformylation of propene to butanal and Shvo/SiO2 to promote the hydrogenation of butanal to butanol. The rate expressions describing the kinetics of each of the catalysts were then used to predict operating conditions required to achieve high conversion of propene to butanol. Under the most favorable conditions examined (H2/CO = 10), an overall yield of 13% to butanol was achieved with 15% propene conversion and 90% aldehyde conversion at a temperature of 413 K. © 2013 Elsevier Inc. All rights reserved