Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metallation-deprotonation (CMD) pathway. Competition experiments were conducted using N-oxides of varying electronic characters, and results revealed an enhancement of rate when using a more electron-deficient species which is in support of a CMD transition state. The effect of base on reaction rate was also examined and it was found that a carboxylate base was required for the reaction to proceed. This led to the conclusion that Pd(OAc)2 plays a pivotal role in the reaction mechanism as more than merely a pre-catalyst, but as a source of acetate base required for the C-H bond cleavage step.

<p>Glycerol is one of the by-products of transesterification of fatty acids for the production of bio-diesel. Value-added products such as hydrogen, wood stabilizers and liquid chemicals from catalytic treatment of glycerol can improve the economics of the bio-diesel production process. Catalytic conversion of glycerol can be used for production of value-added liquid chemicals. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glycerol conversion to liquid chemical products in the presence of acid catalysts. </p><p>Central composite design for response surface method was used to design the experimental plan. Experiments were performed in a fixed-bed reactor using HZSM-5, HY, silica-alumina and ã-alumina catalysts. The temperature, carrier gas flow rate and weight hourly space velocity (WHSV) were maintained in the range of 350-500 oC, 20-50 mL/min and 5.40-21.60 h -1, respectively. </p><p>The main liquid chemicals detected in liquid product were acetaldehyde, acrolein, formaldehyde and hydroxyacetone. Under all experimental conditions complete glycerol conversion was obtained over silica-alumina and ã-alumina. A maximum liquid product yield of approximately 83 g/100g feed was obtained with these two catalysts when the operating conditions were maintained at 380 oC, 26 mL/min and 8.68 h-1. Maximum glycerol conversions of 100 wt% and 78.8 wt% were obtained in the presence of HY and HZSM-5 at temperature, carrier gas flow rate and WHSV of 470 oC, 26 mL/min and 8.68 h-1. HY and HZSM-5 produced maximum liquid product of 80.9 and 59.0 g/100 g feed at temperature of 425 and 470 oC, respectively.</p><p>Silica-alumina produced the maximum acetaldehyde (~24.5 g/100 g feed) whereas ã-alumina produced the maximum acrolein (~25 g/100 g feed). Also, silica-alumina produced highest formaldehyde yield of 9g/100 g feed whereas HY produced highest acetol yield of 14.7 g/100 g feed. The effect of pore size of these catalysts was studied on optimum glycerol conversion and liquid product yield. Optimum conversion increased from 80 to 100 wt% and optimum liquid product increased from 59 to 83.3 g/100 g feed when the pore size of catalyst was increased from 0.54 in case of HZSM-5 to 0.74 nm in case of HY, after which the effect of pore size was minimal.

No description available.

Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metallation-deprotonation (CMD) pathway. Competition experiments were conducted using N-oxides of varying electronic characters, and results revealed an enhancement of rate when using a more electron-deficient species which is in support of a CMD transition state. The effect of base on reaction rate was also examined and it was found that a carboxylate base was required for the reaction to proceed. This led to the conclusion that Pd(OAc)2 plays a pivotal role in the reaction mechanism as more than merely a pre-catalyst, but as a source of acetate base required for the C-H bond cleavage step.

Catalytic combustion is an efficient method to reduce pollutant emissions produced by a variety of fuels. In this thesis, the use of iron pentacarbonyl (Fe(CO)5) as a catalyst precursor in the combustion of natural gas is experimentally studied. The counter-flow diffusion flame burner is employed as the experimental apparatus. The products of combustion are analyzed by using a Gas Chromatograph (GC) to quantitate the effects of adding the catalyst. The experimental setup is such that a mixture of methane (CH4) and nitrogen (N2) is fed from the bottom burner while a mixture of oxygen (O2) and air is supplied from the top burner. The combustion of natural gas without catalyst is first characterized. The oxidizer and fuel flow parameters are set up so that a stable, flat blue flame is formed close to the centre plane between the two burners upon ignition. The experimental results agree with the literature data and the numerical predictions from CHEMKIN software. To investigate and evaluate the performance of iron-containing catalysts on emission reduction, a small amount of separated nitrogen flow is used to carry iron pentacarbonyl into the flame through the central port of the fuel-side burner. Catalytic combustion produces an orange flame. Compared with the non-catalytic combustion data, it is found that carbon monoxide (CO) and soot precursor acetylene (C2H2) are reduced by 80% to 95% when 7453ppm iron pentacarbonyl is added.

As a means to produce high pressure hydrogen in order to reduce compression penalty, we propose to reform liquid fuel (e.g., bio-ethanol) in supercritical water (pressure above 221 bar and temperature greater than 374°C). Catalytic ethanol reforming in supercritical water for hydrogen production has been carried out in a high pressure packed bed reactor made of Inconel-625. Since Inconel-625 contains mainly nickel, it is expected that the reactor itself can be active toward ethanol reforming. Therefore, a series of tests were first performed in the empty reactor, whose results are a benchmark when studying reforming in the presence of a catalyst. Ethanol reforming in the empty reactor was studied in the temperature range of 450 to 600°C and showed coking/plugging problem at 575°C and above. The ethanol conversion with the empty reactor could be as high as 25% at 550°C and residence time of about one minute. The main reaction products with the empty reactor were H2, CO and CH4. A catalyst screening study was performed to investigate the performance of nickel and cobalt as active metals, supported on γ-Al2O3, α-Al2O3, ZrO2 and YSZ for temperatures between 475°C and 550°C. The presence of the catalyst did increase the activity of ethanol reforming, especially at higher temperatures. All experiments in the catalyst screening study were carried out with non-reduced catalysts. Nickel catalysts were found more active than cobalt, likely because of higher reducibility. Indeed, the higher amount of oxygen in Co3O4 compared to NiO requires more hydrogen to fully reduce the metal oxides. Both Ni/γ-Al2O3 and Co/γ-Al2O3 showed little activity below 500°C, and led to failed experiments due to coking/plugging at temperatures of 525°C and above. The strong acid sites on γ-Al2O3 are responsible for high selectivity toward ethylene, a known coke precursor. The support α-Al2O3 in combination with Ni was active, but yielded lower H2 selectivity and higher CH4 selectivity than the zirconia-based catalysts. The Co/α-Al2O3 shows low activity. The ZrO2-based catalysts were active and yielded high H2 selectivity, but were found very fragile. Finally, the YSZ support was strong and yielded good conversion. Below 550°C the activity of Ni/YSZ is higher than that of Co/YSZ, but at 550°C both catalysts yield nearly complete conversion. The advantage of Co/YSZ is then higher H2 selectivity and lower CH4 selectivity compared to Ni/YSZ. Therefore, Co/YSZ was selected for a more detailed study. The effect of temperature, flowrate, residence time, catalyst weight, Co loading, concentration, and pretreatment with H2 were considered. Two methods for catalyst reduction were applied: ex-situ reduction where the catalyst is reduced in a different reactor and in-situ reduction where the catalyst is reduced in the SCW reactor prior to ethanol reforming. At 550°C, Co/YSZ converts all ethanol for residence times as low as 2 s, even with non-reduced catalyst. At 500°C the activity of the in-situ and ex-situ reduced catalysts were similar and greater than for the non-reduced catalyst. At 475°C the ex-situ reduced catalyst showed low activity, comparable to that of the non-reduced catalyst, but the in-situ reduced catalyst yielded much higher conversion. The better performance of the in-situ reduced catalyst was attributed to active metal sites on the reactor’s wall after pre-treatment in H2. The low activity of the ex-situ reduced catalyst is due to the fact that, when exposed to supercritical water for less than 30 minutes, it re-oxidized to CoO. The temperature of 475°C is then too low to generate sufficient hydrogen that will start reducing the catalyst. Finally, analysis of reaction pathways for ethanol reforming over Co/YSZ showed that the reaction proceeds mostly via ethanol dehydrogenation to form acetaldehyde, the latter species reacting with lattice oxygen on the catalyst to produce acetone and CO2. Acetone is then reformed by water into CO and H2. Finally, H2 and CO react via the methanation reaction to form CH4. Over Co/YSZ it was found that the water-gas shift reaction is fast (CO selectivity most of the time is less than 0.5%), but the methanation reaction is kinetically controlled. Stopping the methanation reaction before equilibrium allowed for H2 selectivity higher than what is expected at equilibrium (likewise, CH4 selectivity is smaller than equilibrium value). For well-controlled reaction Co/YSZ is a promising catalyst that can be highly selective toward hydrogen during ethanol reforming in supercritical water.

As a means to produce high pressure hydrogen in order to reduce compression penalty, we propose to reform liquid fuel (e.g., bio-ethanol) in supercritical water (pressure above 221 bar and temperature greater than 374°C). Catalytic ethanol reforming in supercritical water for hydrogen production has been carried out in a high pressure packed bed reactor made of Inconel-625. Since Inconel-625 contains mainly nickel, it is expected that the reactor itself can be active toward ethanol reforming. Therefore, a series of tests were first performed in the empty reactor, whose results are a benchmark when studying reforming in the presence of a catalyst. Ethanol reforming in the empty reactor was studied in the temperature range of 450 to 600°C and showed coking/plugging problem at 575°C and above. The ethanol conversion with the empty reactor could be as high as 25% at 550°C and residence time of about one minute. The main reaction products with the empty reactor were H2, CO and CH4. A catalyst screening study was performed to investigate the performance of nickel and cobalt as active metals, supported on γ-Al2O3, α-Al2O3, ZrO2 and YSZ for temperatures between 475°C and 550°C. The presence of the catalyst did increase the activity of ethanol reforming, especially at higher temperatures. All experiments in the catalyst screening study were carried out with non-reduced catalysts. Nickel catalysts were found more active than cobalt, likely because of higher reducibility. Indeed, the higher amount of oxygen in Co3O4 compared to NiO requires more hydrogen to fully reduce the metal oxides. Both Ni/γ-Al2O3 and Co/γ-Al2O3 showed little activity below 500°C, and led to failed experiments due to coking/plugging at temperatures of 525°C and above. The strong acid sites on γ-Al2O3 are responsible for high selectivity toward ethylene, a known coke precursor. The support α-Al2O3 in combination with Ni was active, but yielded lower H2 selectivity and higher CH4 selectivity than the zirconia-based catalysts. The Co/α-Al2O3 shows low activity. The ZrO2-based catalysts were active and yielded high H2 selectivity, but were found very fragile. Finally, the YSZ support was strong and yielded good conversion. Below 550°C the activity of Ni/YSZ is higher than that of Co/YSZ, but at 550°C both catalysts yield nearly complete conversion. The advantage of Co/YSZ is then higher H2 selectivity and lower CH4 selectivity compared to Ni/YSZ. Therefore, Co/YSZ was selected for a more detailed study. The effect of temperature, flowrate, residence time, catalyst weight, Co loading, concentration, and pretreatment with H2 were considered. Two methods for catalyst reduction were applied: ex-situ reduction where the catalyst is reduced in a different reactor and in-situ reduction where the catalyst is reduced in the SCW reactor prior to ethanol reforming. At 550°C, Co/YSZ converts all ethanol for residence times as low as 2 s, even with non-reduced catalyst. At 500°C the activity of the in-situ and ex-situ reduced catalysts were similar and greater than for the non-reduced catalyst. At 475°C the ex-situ reduced catalyst showed low activity, comparable to that of the non-reduced catalyst, but the in-situ reduced catalyst yielded much higher conversion. The better performance of the in-situ reduced catalyst was attributed to active metal sites on the reactor’s wall after pre-treatment in H2. The low activity of the ex-situ reduced catalyst is due to the fact that, when exposed to supercritical water for less than 30 minutes, it re-oxidized to CoO. The temperature of 475°C is then too low to generate sufficient hydrogen that will start reducing the catalyst. Finally, analysis of reaction pathways for ethanol reforming over Co/YSZ showed that the reaction proceeds mostly via ethanol dehydrogenation to form acetaldehyde, the latter species reacting with lattice oxygen on the catalyst to produce acetone and CO2. Acetone is then reformed by water into CO and H2. Finally, H2 and CO react via the methanation reaction to form CH4. Over Co/YSZ it was found that the water-gas shift reaction is fast (CO selectivity most of the time is less than 0.5%), but the methanation reaction is kinetically controlled. Stopping the methanation reaction before equilibrium allowed for H2 selectivity higher than what is expected at equilibrium (likewise, CH4 selectivity is smaller than equilibrium value). For well-controlled reaction Co/YSZ is a promising catalyst that can be highly selective toward hydrogen during ethanol reforming in supercritical water.

<p>Glycerol is one of the by-products of transesterification of fatty acids for the production of bio-diesel. Value-added products such as hydrogen, wood stabilizers and liquid chemicals from catalytic treatment of glycerol can improve the economics of the bio-diesel production process. Catalytic conversion of glycerol can be used for production of value-added liquid chemicals. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glycerol conversion to liquid chemical products in the presence of acid catalysts. </p><p>Central composite design for response surface method was used to design the experimental plan. Experiments were performed in a fixed-bed reactor using HZSM-5, HY, silica-alumina and ã-alumina catalysts. The temperature, carrier gas flow rate and weight hourly space velocity (WHSV) were maintained in the range of 350-500 oC, 20-50 mL/min and 5.40-21.60 h -1, respectively. </p><p>The main liquid chemicals detected in liquid product were acetaldehyde, acrolein, formaldehyde and hydroxyacetone. Under all experimental conditions complete glycerol conversion was obtained over silica-alumina and ã-alumina. A maximum liquid product yield of approximately 83 g/100g feed was obtained with these two catalysts when the operating conditions were maintained at 380 oC, 26 mL/min and 8.68 h-1. Maximum glycerol conversions of 100 wt% and 78.8 wt% were obtained in the presence of HY and HZSM-5 at temperature, carrier gas flow rate and WHSV of 470 oC, 26 mL/min and 8.68 h-1. HY and HZSM-5 produced maximum liquid product of 80.9 and 59.0 g/100 g feed at temperature of 425 and 470 oC, respectively.</p><p>Silica-alumina produced the maximum acetaldehyde (~24.5 g/100 g feed) whereas ã-alumina produced the maximum acrolein (~25 g/100 g feed). Also, silica-alumina produced highest formaldehyde yield of 9g/100 g feed whereas HY produced highest acetol yield of 14.7 g/100 g feed. The effect of pore size of these catalysts was studied on optimum glycerol conversion and liquid product yield. Optimum conversion increased from 80 to 100 wt% and optimum liquid product increased from 59 to 83.3 g/100 g feed when the pore size of catalyst was increased from 0.54 in case of HZSM-5 to 0.74 nm in case of HY, after which the effect of pore size was minimal.

X-ray crystallography provides detailed information of the atomic structure of macromolecules that aides in the understanding of their molecular function. In this study, the three-dimensional structures of the Toluene-4-monooxygenase catalytic effector protein (T4moD), NAD(P)H oxidase and choline oxidase were determined. The structures of wild-type and two mutant isoforms of T4moD were solved up to 1.7 resolution. Results from the crystallographic studies indicate that there are significant differences between the X-ray structure and the structure previously solved by NMR. The high-resolution structures have helped to define the potential differences in electrostatic surfaces that may govern the feasibility of protein-protein interactions and also reveal a single, well-defined cavity suitable for toluene binding that has substantial different electrostatic properties among the effector protein family members. The structure of NAD(P)H oxidase from Lactobacillus sanfranciscensis was determined to 1.8 resolution. The flavoenzyme is of considerable interest as it catalyzes the oxidation of two equivalents of NAD(P)H and reduces one equivalent of oxygen to yield two equivalents of water without releasing hydrogen peroxide from the active site. The structure reveals the presence of a redox active cysteine residue that exists as a sulfenic acid and plays an important mechanistic role by reducing hydrogen peroxide to water. Additionally, a tightly bound ADP molecule was discovered in the enzyme which is hypothesized to play an important role in influencing the dual substrate specificity exhibited by the enzyme. The structure of choline oxidase from Arthrobacter globiformis was solved to 1.86 resolution. Choline oxidase catalyzes the four-electron oxidation of choline to glycine betaine via two sequential FAD-dependent reactions. The structure reveals a cavity within the active site, which is suitable for choline binding. This allows for the identification of the putative binding site for choline and residues involved in substrate-binding and catalysis. Additionally, the structure reveals a highly distorted FAD cofactor that contains a C4a-adduct that is proposed to be either an FAD-C4a-OH or FAD-C4a-O2- complex.

Abstract Today everyone have a lot of meetings. The meetings¡¦ efficiency is quite low and group decision-making quality is bad. In foreign, many methods have good effects on it. Open space technology is one of them. But it has some conditions and assumptions which don¡¦t fit our culture and the conditions of our companies. We have to improve Open space technology to draw its effects. We improve it according to our assumptions and principles. We also assist it with some technologies, like Talking stick, circling, and catalytic mechanism. They all have outstanding and stable results. They can help Open space technology to overcome the deficit of ideal conditions. This research¡¦s main point is to introduce and collect the creative ways of the improved Open space technology. In two hospitals, we can see the improved Open space technology which has obvious effects and promote the group decision-making quality a lot. It still can get good results under the deficit of ideal conditions. We conclude that it has 9 traits as followed: 1. It lowers the barrier of inertia. 2. Interactions 3. Positive feedback 4. Participation 5. The form of activity 6. Safety 7. Closer contact with others 8. Appreciative attitude 9. Truly contribution This research is a initial research and introduction of the improved Open space technology. We suggest other researchers can popularize the improved Open space technology and get the more generalization results.