The partial oxidation of methanol to formaldehyde with air as oxidant has been studied with supported monometallic and bimetallic catalysts of copper and silver over a range of temperature and contact times. This was done to investigate the influence the bimetallics could possibly have on either the reaction pathways and/or the product(s) selectivity of the oxidation of methanol. Characterisation of these catalysts was performed by nitrogen adsorption and porosity measurements, XRD, and IR spectroscopy of adsorbed methanol and of adsorbed CO. These results indicated no crystalline phases of the loaded metals to be present. CO adsorption showed the presence of small cluster metal atoms on the surface of the catalysts. The reduction peaks from TPR also revealed the presence of partially oxidised and dispersed metal atoms. Infra-red studies of methanol adsorbed on these sample catalysts revealed the presence of intermediate methoxy and formate species which are believed to be formed in the course of the reactions. Results showed the monometallic copper and silver catalyst to be more active than the bimetallics. Although formaldehyde selectivities and yields were generally low, they were highest for the bimetallics supported on the silica catalyst than the monometalics and alumina supported samples. Copper-silver interaction in the bimetallic was proposed to enhance the reduction of the silver that enhanced the selectivity to formaldehyde. In particular under conditions, low conversions of methanol saw highest selectivities to formaldehyde. There was also a pronounced effect of the supports on product distribution and activities with the alumina based samples being more active than the silica supported ones, with the product distributions on the alumina supported significantly showing high yields of DME while the silica showed high yield for methyl formate with COx and CH4 detected in small quantities on all the catalysts within the parameters investigated.

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Thesis (M.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / In work reported by Lichtin, Rosenberg, and Imamuras it was found that water added before irradiation of aerated methanol had a surprising effect on peroxide yields. In the absence of water, no hydrogen peroxide was produced during radiolysis, but in the presence of about 0.5 weight-percent water the yield of peroxide increased abruptly from zero to a plateau G value of 2.8. Attempts to reproduce these data were unsuccessful, however, and it was discovered that the observed effect of water on hydrogen peroxide yields is post-radiolytic in nature. Identical peroxide yields were produced during radiolysis of both dry methanol samples and samples to which water was added before radiolysis. In the dry samples, however, hydrogen peroxide was found to decompose with approximately first-order kinetics. Addition of water subsequent to irradiation inhibited decay. No significant change was noted in the concentration of radiolytically-generated formaldehyde during the period of peroxide decay. The average G(H2o2), obtained by extrapolation of the decomposition curve of radiolytically-generated hydrogen peroxide in dry methanol back to the time of the removal ofthe sample from the 60Co source, was 3.28 + 0.12. Half-decay times varied widely due to the variable dryness of the methanol. It was found that solutions of non-radiolytic hydrogen peroxide in dry methanol likewise underwent first-order decay. The rate of decomposition in these solutions could be accelerated by an increase in temperature or by subsequent radiolysis. The addition of formaldehyde was also found to accelerate peroxide decomposition, although no significant change was noted in the formaldehyde concentration. Methyl hydroperoxide was tentatively identified as a radiation product with a G value of about 0.2. Analysis of a radiolytic sample in which hydrogen peroxide had decomposed completely indicated that methyl hydroperoxide had not undergone similar decay. The nature of the hydrogen peroxide decomposition process is still unknown. Speculation concerning the decay inhibiting effect of water has been developed from several points of view: medium effects, specific interactions, and the possible effects of impurity. Influences of added sulfuric acid and methyl borate on radiolytic peroxide yields were also studied briefly. / 2031-01-01

The requirement of external carbon for conventional biological nitrogen removal (BNR) process has stimulated research on more resource-efficient treatment technologies. Bioconversion of methane to methanol using ammonia oxidizing bacteria (AOB), a process relies on the activity of ammonia monooxygenase expressed by AOB, offers an alternative and sustainable carbon source as all the components (ammonia, AOB, and methane) are often available within the water resource recovery facilities. Though the concept of biomethanol production using AOB has been proposed decades ago, previous studies have been primarily focused on the kinetics of methane oxidation in axenic batch cultures. In this study, the overall objectives were to (1) develop a platform for biomethanol production using AOB in a continuous process and (2) investigate the mechanism of methane cometabolism in AOB under chemostat conditions. Pure culture AOB (Nitrosmonas europaea and Nitrosomonas eutropha) and mixed culture nitrifying consortia were cultivated in bioreactors and continuously exposed to methane to study the responses of nitrifying bacteria at reactor level (nitrification performance) and molecular level (genes and proteins expression). The mixed culture experiments successfully demonstrated continuous biomethanol production with two types of bioreactor configurations. Acclimation of the mixed culture nitrifying consortia to co-exposure and co-oxidation of ammonia and methane were shown at multiple levels (reactor performance, biomass concentrations, bacterial activities, and genes expression). Furthermore, the accumulation of nitrite and a more substantive impact on nitrite oxidizing bacteria growth (compared to AOB) indicated the possibility for partial nitrification (ammonia-N to nitrite-N) coupled with biomethanol production, thereby opening the prospect for even more resource-efficient concurrent carbon and nitrogen management and removal. On the other hand, experiments with axenic AOB culture showed that methane exposure negatively and reversibly affected ammonia oxidation and AOB growth. Proteomics and gene expression data from pure culture experiments suggested that AOB modulating their catabolic (energy synthesis) and anabolic (biomass synthesis) pathways in response to methane exposure. Moreover, N. eutropha experiments demonstrated the potential adaptation of AOB to methane supplementation. Comparative transcriptomic analysis of methane cometabolism in N. europaea and N. eutropha showed that AOB upregulated genes involved in ATP production while downregulated genes involved in NADH production, organic molecules synthesis and cell division. In conclusion, this work provides insights for the process optimization for integrated AOB-mediated biomethanol production and (full- or partial-) nitrification processes as well as structured process modeling to facilitate such optimization and process scale-up and adoption. The whole transcriptomic analysis delineates a comprehensive and detailed view regarding methane cometabolism in AOB.

A solar based integrated system for hydrogen and methanol production is investigated. Energy and exergy analyses of a hydrogen production plant, thermodynamic assessment of methanol synthesis plant, and exergy analysis of the integrated solar based system for hydrogen and methanol production are performed. The analysis of hydrogen production is found to be essential in order to investigate for further design parameters for methanol synthesis procedure. The present analysis shows the effects of temperature and current density on hydrogen production. Thermodynamic parameters of the methanol synthesis plant, such as temperature and pressure, appear to be an important role in methanol production. Based on the methods of physical domain of the system, the optimum temperature of methanol synthesis is obtained for the final design of the methanol plant. It is concluded that increasing pressure improves the methanol synthesis process; however, methanol conversion takes place at 493 K. The energy and exergy efficiencies of the system are reduced by 30% if the electrolyser operates at 300 K. The efficiencies of the system are also highly dependent on the solar intensity. The system efficiencies can be tripled if the intensity of solar radiation is increased to 600 W/m2 instead of 250 W/m2. / UOIT

The performance of a Direct Methanol Fuel Cell has been experiment and analysis in this research. The performance of Direct Methanol Fuel Cell were tested by changing different parameter, such as methanol concentration, temperature, and the effect of carbon dioxide. This influence include transient and steady-state respond. Through the experiment and analysis, we hope we could understand the important factors which influence the performance of the DMFC. This experiment use Nafion® as membrane electrode assembly, and the ratio of flow channel area to total electrode area is 58%. The performance of the single cell was enhanced by increasing methanol concentration as the experiment result, no matter transient or steady-state respond. The best performance was obtained from 2M. The performance at transient or steady-state was also improved by increasing methanol/cell temperature. The product of the reaction, carbon dioxide, will cause more influence when cell work at higher current. In addition, there are few carbon dioxide which will appear as gaseous state.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 183-191).

Phosphoryl transfer reactions are vital to life. In response to the slow intrinsic rates of phosphoryl transfer, Nature has evolved a series of enzymes designed to accelerate these reactions and allow them to occur at biologically relevant rates. These metallo-enzymes are largely characterized by bi- or tri-nuclear active sites with effective dielectric constants that more closely resemble those of organic solvents than water. This project was designed to better understand the mechanisms by which metalloenzymes cleave phosphodiesters with poor leaving groups. The stability of the phosphodiester is central to the storage of genetic information in DNA and RNA. The cleavage of a series of more reactive RNA models, 2-hydroxylpropyl aryl phosphates 1a-g, catalyzed by a dinuclear Zn(II)2 complex of 53 in methanol was explored. A solution of 53:Zn(II)2:(-OCH3) was observed to accelerate the decomposition of 1a-g with rates that were 10^11-10^12-fold greater than the methoxidepromoted reaction at ss pH 9.47, approaching rate accelerations achieved by natural enzymes. The remarkable activity of 53:Zn(II)2:(-OCH3) and 36:Zn(II)2:(-OCH3) towards the cleavage of 1a-g probed the study of the decomposition of diribonucleotides(3'->€™ 5')UpU and (3'->€™ 5'€™)ApC in methanol. The 53:Zn(II)2:(-OCH3)- and 36:Zn(II)2:(-OCH3)-catalyzed decomposition of UpU achieved k2 values of 1.21 ± 0.17 and (7.04 ± 0.99) x 10^-2 M^-1s^-1. The reactivity of ApC in the presence of these systems was unimpressive, however Zn(II) ions in ethanol resulted in the isomerization of 3'->€™ 5'€™)ApC to (2'->™ 5'€™)ApC providing support for the existence of a pentacoordinate phosphorane intermediate. The pentacoordinate phosphorane was further explored through the reaction of 36:Zn(II)2:(-OCH3) with the cyclic phosphate 58 and 2-hydroxylpropyl methyl phosphate (59). In the presence of 36:Zn(II)2:(-OCH3) the rate of isomerization of 59/59a (kobs = (4.7 ± 0.5) x 10^-3 s^-1) exceeded that of expulsion of the methoxy group (kobs = 1.62 x 10^-3 s^-1), thus confirming the existence of a pentacoordinate phosphorane intermediate (60)and providing support for a two-step phosphodiester cleavage reaction. The catalytic efficiency of 36:Zn(II)2:(-OCH3) towards the cleavage of stable phosphodiesters probed its application towards the decomposition of dimethyl phosphate (2) in methanol-d4. The exchange of OCH3 for OCD3 occurred with kcatmax = (2.27 ± 0.03) x 10^-6 s^-1. / Thesis (Master, Chemistry) -- Queen's University, 2008-09-12 13:09:42.427