Metal- and halogen-free synthesis of ordered mesoporous carbon materials

We thank the University of St Andrews for the PhD scholarship of FS.Mesoporous carbon materials are of great interest as catalyst supports. However, the presence of impurities such as the metal or halide ions which are often used to catalyse the polymerisation and condensation reactions in their preparation can be poisonous to the final catalyst product. For this reason, in this work, metal- and halogen-free mesoporous polymer and carbon materials (OMCs) were synthesised using a modified two phase method employing alternative polymerisation and condensation catalysts. The OMC materials synthesised exhibit a highly ordered two dimensional hexagonal arrangement of cylindrical mesopores, as revealed by small angle XRD, gas physisorption and TEM analysis, and have typical specific surface areas of ca. 600 m2/g, pore size of ca. 7.0 nm, and pore volume of approximately 0.60 cm3/g. Their physical evolution with increasing calcination temperature is examined as are the effects of varying synthesis parameters on the nature of the final mesostructure.PostprintPeer reviewe

Acetylene hydrogenation over structured Au-Pd catalysts

Acknowledgements We thank the University of Aberdeen for financial support and Dr K. McManus (University of Aberdeen) for performing preliminary experiments with these samples. Electron microscopy and EDS were performed by RTB at the Electron Microscopy Facility, University of St Andrews.Peer reviewedPostprin

1993 Accounting Hall of Fame induction : Richard T. Baker Accounting Hall of Fame membership [1993]

1993 Accounting Hall of Fame Induction: Richard T. Baker with introduction by Ray J. Groves (Chairman, Ernst & Young); Induction citation by Thomas J. Burns (Deloitte and Touche Professor, The Ohio State University); Response by Richard T. Baker (Chairman Emeritus, Ernst & Whinney

Radiation content of Conformally flat initial data

We study the radiation of energy and linear momentum emitted to infinity by the headon collision of binary black holes, starting from rest at a finite initial separation, in the extreme mass ratio limit. For these configurations we identify the radiation produced by the initially conformally flat choice of the three geometry. This identification suggests that the radiated energy and momentum of headon collisions will not be dominated by the details of the initial data for evolution of holes from initial proper separations $L_0\geq7M$. For non-headon orbits, where the amount of radiation is orders of magnitude larger, the conformally flat initial data may provide a relative even better approximation.Comment: 4 pages, 4 figure

Coordination-controlled electrodeposition of palladium/copper thin films onto a pyridine-terminated self-assembled monolayer

Support by the Chinese Scholarship Council and the University of St Andrews for a stipend (Z. Y.) are gratefully acknowledged. Electron microscopy was carried out at the Electron Microscopy Facility, School of Chemistry, University of St Andrews and we acknowledge recent funding for the Facility from the EPSRC (EP/T019298/1, EP/L017008/1) and the EPSRC Strategic Resources Grant (EP/R023751/1).A scheme for the electrodeposition of ultrathin bimetallic layers on top of a self-assembled monolayer (SAM) is investigated which combines the deposition of one metal (Pd) coordinated to a functionalized SAM (3-(4-pyridine-4-yl-phenyl)-propane-1-thiol, PyP3) on Au/mica with another metal (Cu) from the bulk electrolyte. The coordination-controlled electrodeposition (CCED) is a four-phase process comprising (i) Pd2+ coordination to the terminal pyridine units of the SAM, (ii) reduction of Pd and nanoparticle formation, (iii) formation of an intermixed shell of Pd and Cu, and (iv) deposition of bulk Cu. Chronoamperometry reveals a fast nucleation phase where Pd nanoparticles form within a few milliseconds and seed the Cu deposition. The Pd-Cu core-shell nature of deposited nanoparticles is confirmed by transmission electron microscopy (TEM). Harnessing the selective coordination of Pd2+ to PyP3, a one-pot procedure is further developed using electrolytes containing both Pd2+ and Cu2+ ions. Thus simplifying complexation and reduction, continuous Pd/Cu films are obtained in a multistep process as verified by scanning tunneling microscopy (STM). With a percolation threshold below 3 nm, CCED, as a SAM-controlled deposition strategy, offers an avenue for generation of ultrathin films.Publisher PDFPeer reviewe

Fixed-bed adsorption of the dye Chrysoidine R on ordered mesoporous carbon

Funding: The authors are grateful to the Ministry of Human Resource Development of the Government of India for financial support through the SPARC initiative (project: SPARC/2018-2019/P307/SL). One of the authors (AM) is thankful to MANIT, Bhopal for providing fellowship support.Herein, the efficiency of an ordered mesoporous carbon (OMC), synthesized through metal and halide free pathways, is evaluated to remove an anionic dye Chrysoidine R through fixed-bed adsorption. Potentially toxic azo dye, Chrysoidine R, was employed as a test and encouraging results are obtained. The bulk removal of the dye was accomplished with 99.77% column saturation and treatment of the exhausted bed of adsorbent with a suitable eluent resulted in almost 100% dye-recovery. The efficiency of the column remained almost unchanged in five adsorption/desorption cycles. The fixed-bed column studies clearly reveal that the OMC is a highly efficient and robust material for large-scale wastewater treatment applications.Publisher PDFPeer reviewe

Deactivation and regeneration of activated carbon-supported Rh and Ru catalysts in the hydrodechlorination of chloromethanes into light olefins

This work analyses the deactivation of activated carbon-supported Rh and Ru (both at 1 wt%) catalysts (Rh/C and Ru/C) in the hydrodechlorination (HDC) of dichloromethane (DCM) and chloroform (TCM). The deactivation can be mainly attributed to the coverage of active metal centres by organometallic species resulting from the chemisorption of reaction products, such as olefins, at the electro-deficient metal sites. With DCM, the activity of Ru/C decreased by more than 80% after 90 h on stream at 250 °C and with a space time of 1.7 kg h mol−1. Under the same conditions, with TCM, the Rh/C and Ru/C catalysts lost 75% of activity after 84 and 54 h on stream, respectively. A regeneration treatment with air at 250 °C allowed complete recovery of the catalytic activity. After each deactivation-regeneration cycle, the selectivity to olefins increased. Therefore, HDC with the catalysts tested provides a promising way for the upgrading of chloromethanes from waste gas streams into light olefinshe authors gratefully acknowledge financial support from FEDER/ Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación/CTM2017-85498-R. M. Martín Martínez acknowledges a postdoctoral grant, 2017-T2/AMB-5668, from the Comunidad de Madrid “Atracción de talento investigador” programm

Observation of the cubic-field splitting of an excited S = 2 manifold in a cubic copper tetramer

EPR measurements on single crystals of Cu40Cl6(triphenylphosphine oxide)4 at liquid helium temperatures in the frequency ranges 14-17 and 34-35 GHz were fitted to a simple cubicS= 2 spin Hamiltonian with g = 2.10 ± 0.01 and a zero-field splitting of(0.53 ± 0.01) em - 1 • From the decrease in intensity of the S = 2 spectrum on cooling below 4.2 K and the absence of an S = 1 spectrum, the S = 2 manifold was deduced to lie ( 14 ± 1) em- 1 above a nonmagnetic ground state. The EPR results are used as a test of the various theories developed to explain the magnetic susceptibility of copper tetramer

Batch and bulk adsorptive removal of anionic dye using metal/halide-free ordered mesoporous carbon as adsorbent

The authors are grateful to the Ministry of Human Resource Development of the Government of India for financial support through the SPARC Project- SPARC/2018–2019/P307/SL. One of the authors (Asna Mariyam) is also grateful to MANIT, Bhopal for providing fellowship assistance. We thank the University of St Andrews for a PhD scholarship for FS. We acknowledge EPSRC Strategic Resources Grant (EP/R023751/1).The present report is an outcome of investigations to assess the adsorptive potential of a synthesized metal- and halide-free variant of ordered mesoporous carbon (OMC) towards an anionic azo dye, Methyl Orange. The results of preliminary studies, carried out in batch mode, helped in setting up the process variables to achieve optimum adsorption conditions. The experimental data were then fitted to Langmuir, Freundlich, Temkin, and Dubinin-Radushkevitch isotherm models. The equilibrium data fitted well to the Langmuir model at 303 K and the monolayer adsorption capacity was 0.33 mmol g−1. The adsorption kinetics were explored by fitting the data to pseudo-first-order and pseudo-second-order kinetic models. The latter described the kinetics well, as indicated by higher regression coefficients. To elucidate the mechanism of mass transfer, various well-known mathematical models were employed. The adsorption of the dye was found to involve particle diffusion. Thermodynamic studies revealed that the adsorptive uptake of Methyl Orange by the OMC was spontaneous (ΔG0 = −23.71 kJ mol−1) and exergonic (ΔH0 = −123.15 kJ mol−1). Finally, the bulk removal of the anionic dye was investigated through column operations followed by column regeneration (desorption) studies. Column saturation of up to 96.55% could be realized. Values for dye recovery reached up to 93.26%. The column efficiency was then evaluated by carrying out three consecutive adsorption/desorption cycles. The results obtained indicated that the adsorbent has a good ability to eliminate Methyl Orange from wastewater, both in batch and column operations.PostprintPeer reviewe