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Zarepour E.,University of New South Wales | Hassan M.,University of New South Wales | Chou C.T.,University of New South Wales | Adesina A.A.,ATODATECH LLC
Proceedings of the 1st ACM International Conference on Nanoscale Computing and Communication, NANOCOM 2014 | Year: 2014

Chemical reactors are designed to efficiently produce highvalue chemical products but at the same time they also produce low-value by-products. The selectivity of a chemical process refers to the proportion of high-value product produced. A nano sensor network (NSN) monitoring the chemical process at the molecule level could help improving the selectivity by preventing the reactions that lead to low value by-products. Therefore, a central requirement to achieve high selectivity by NSN is reliable communication. A challenge to realising reliable communication within a chemical reactor is its time-varying chemical composition, which in turn creates a time-varying radio channel and noise. The sensor nodes therefore need to adjust their transmission power according to the chemical composition while maintaining a low overall power budget. We show that this problem can be modelled as a Markov Decision Process (MDP). However, the MDP solution requires the sensors to know the composition of the reactor at each time instance, which is prohibitive. We therefore derive off-line time-based policies that these sensors can use. We illustrate our work by using an important chemical process for fuel production and demonstrate the performance of our proposed off-line policies against the optimal MDP policy.

Setiawan A.,University of Newcastle | Setiawan A.,Malikussaleh University | Kennedy E.M.,University of Newcastle | Dlugogorski B.Z.,Murdoch University | And 2 more authors.
Catalysis Today | Year: 2015

Nano-sized Co3O4, Fe2O3, Au/Co3O4 and Au/Fe2O3 catalysts were prepared and evaluated for catalytic combustion of lean methane-air mixtures. Characteristics and catalytic activities under dry and wet feed conditions were investigated at gas hourly space velocities up to 100000h-1 mimicking the typical flow and conversion requirements of a catalytic system designed to treat a ventilation air methane stream. In order to gain a better understanding of the interaction between H2O and the catalyst surface, temperature-programmed desorption of water over fresh and used samples were studied, and supported by other catalyst characterization techniques such as N2-adsorption desorption, XRD, TEM, SEM and XPS analyses. The activity measurements of the catalysts studied identify Co3O4 as the most active material. Co-precipitating gold particles with cobalt oxide or iron oxide do not enhance the activity of the catalyst, which is most likely due to blocking the active site of support by the gold particle. The presence of strong hydroxyl bonds on the catalyst surface is substantiated by TPD and XPS analyses, and is suggested to be responsible for the rapid deactivation of Fe2O3 and Au/Fe2O3 catalysts. © 2014 Elsevier B.V.

Sanchez G.,University of Newcastle | Friggieri J.,University of Newcastle | Adesina A.A.,ATODATECH LLC | Dlugogorski B.Z.,Murdoch University | And 2 more authors.
Catalysis Science and Technology | Year: 2014

A continuous process for the conversion of glycerol to allyl alcohol, where ammonia or organic acids are added to the feed as sacrificial reductants, was investigated. Significant enhancement on the rate of formation and yield of the allyl alcohol is observed with some of the reducing agents examined over an alumina-supported iron catalyst. Optimising the molar ratio of the reductant relative to feed glycerol results in an increase in the yield of allyl alcohol from 9% (in the absence of additives) to 11.3% with ammonia, 15.1% with ammonium hydroxide, 17.8% with oxalic acid and 19.5% with formic acid. Moreover, the addition of other organic acids, which are produced in a typical glycerol conversion experiment, was studied. However, acetic and propanoic acids had little effect on the rate of formation of allyl alcohol. Analysis of the product distribution in the liquid and gas phases when oxalic and formic acids were added suggests a two-step process for the formation of allyl alcohol under the operating conditions of the reaction; the initial step involves the dehydration of glycerol while the second comprises the reduction of the species produced in step one. © the Partner Organisations 2014.

Setiawan A.,University of Newcastle | Setiawan A.,Malikussaleh University | Friggieri J.,University of Newcastle | Hosseiniamoli H.,University of Newcastle | And 4 more authors.
Physical Chemistry Chemical Physics | Year: 2016

A novel Pd supported on TS-1 combustion catalyst was synthesized and tested in methane combustion under very lean and under highly humid conditions (<1%). A notable increase in hydrothermal stability was observed over 1900 h time-on-stream experiments, where an almost constant, steady state activity obtaining 90% methane conversion was achieved below 500 °C. Surface oxygen mobility and coverage plays a major role in the activity and stability of the lean methane combustion in the presence of large excess of water vapour. We identified water adsorption and in turn the hydrophobicity of the catalyst support as the major factor influencing the long term stability of combustion catalysts. While Pd/Al2O3 catalyst shows a higher turn-over frequency than that of Pd/TS-1 catalyst, the situation reversed after ca. 1900 h on stream. Two linear regions, with different activation energies in the Arrhenius plot for the equilibrium Pd/TS-1 catalyst, were observed. The conclusions were supported by catalyst characterization using H2-chemisorption, TPD, XPS analyses as well as N2-adsorption-desorption, XRD, SEM, TEM. The hydrophobicity and competitive adsorption of water with oxygen is suggested to influence oxygen surface coverage and in turn the apparent activation energy for the oxidation reaction. © the Owner Societies 2016.

Zarepour E.,University of New South Wales | Hassan M.,University of New South Wales | Chou C.T.,University of New South Wales | Adesina A.A.,ATODATECH LLC
Proceedings of the 2nd ACM International Conference on Nanoscale Computing and Communication, ACM NANOCOM 2015 | Year: 2015

A novel self-powered sensing and communication architecture for remote detection of chemical reactions is proposed. It is assumed that pyroelectric nanogenerators fitted with Graphene-based nano-antennas radiating in the Terahertz band (0.1-10THz) are embedded in the catalyst surface where different types of chemical reactions take place. Each reaction consumes or dissipates some heat, which causes temperature fluctuations on the catalyst surface. A pyroelectric nanogenerator harvests electrical energy from each temperature fluctuation and use the energy to transmit a THz pulse of proportional amplitude. Because different types of reactions dissipate different amounts of energy, we show that a remote receiver can detect the reaction type from the received pulse energy. The accuracy of reaction detection at the receiver, however, is compromised by the noise and attenuation of the THz channel, which makes it difficult to detect reactions from a longer distance. Using simulations, it is shown that dynamic frequency selection within the THz band based on the expected chemical composition of the reactor at any given time can help extending the distance of remote reaction detection. © 2015 ACM.

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