Richard P. Noceti

New developments in the photocatalytic conversion of methane to methanol

Abstract Investigation of direct conversion of methane to transportation fuels has been an on-going effort at FETC for over 14 years. One of our current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. Research in our laboratory is directed toward adapting the chemistry developed for photolysis of water to that of methane conversion. The reaction sequence of interest uses visible light, a doped tungsten oxide photocatalyst and an electron transfer molecule to produce a hydroxyl radical. Hydroxyl radical can then react with a methane molecule to produce a methyl radical. In the preferred reaction pathway, the methyl radical then reacts with an additional water molecule to produce methanol and hydrogen.

Direct Conversion of Methane to Liquid Hydrocarbons Through Chlorocarbon Intermediates

Abstract The chemical activation of methane and its subsequent conversion to oxygenates or higher hydrocarbons have been the objects of intensive research in the past several years. At the Pittsburgh Energy Technology Center, a novel combination of two existing process concepts has been examined and appears capable of producing higher hydrocarbons from methane with high yield and selectivity. Methane, oxygen, and hydrogen chloride are reacted over an oxyhydrochlorination catalyst in the first stage to produce methyl chloride and water. In the second stage, the methyl chloride is converted to higher hydrocarbons, namely paraffins, olefins, aromatics, and cycloparaffins, over a zeolite, such as ZSM-5. In the process concept described, the final hydrocarbon mixture is largely in the gasoline (C 4 , C 10 ) boiling range.

Photocatalytic conversion of methane

Investigation of the direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of our current areas of research is the conversion of methane to methanol under mild conditions using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. Research in our laboratory is directed toward applying techniques developed for the photochemical splitting of water to methane conversion. The reaction sequence of interest initially produces a hydroxyl radical with the aid of a doped tungsten oxide photocatalyst and an electron transfer molecule. Hydroxyl radical can then react with a methane molecule to produce a methyl radical. In the preferred reaction pathway, the methyl radical then reacts with an additional water molecule to produce methanol and hydrogen.

Coal-derived asphaltenes: effect of phenol content and molecular weight on viscosity of solutions

Phenol contents and molecular weights of coal-derived asphaltenes are shown to affect the viscosity of their solutions. Phenol contents were determined by non-aqueous titrimetry. Intermolecular aggregation probably involving hydrogen bonding is a prime factor in the increase in viscosity found with increased asphaltene concentration in a reference solvent system composed of an 8812 (wtwt) mixture of 1-methylnaphthalene and o-cresol. Aggregation effects are greater for those asphaltenes with relatively higher phenol contents. Asphaltenes were separated into fractions of different polarity by adsorption chromatography. The more polar subfraction was found to increase viscosity in the reference solvent to a greater extent than the less polar subfraction. The logarithmic viscosity numbers of solutions of the asphaltenes and their subfractions are correlated by a linear combination of molecular weights and phenol contents. It is concluded that an effective means of reducing the viscosity of coal-derived liquids would be to reduce the phenol content of the asphaltene fraction.

Coal-derived asphaltenes. Relationship between chemical character and process history

Abstract The chemical character of asphaltenes isolated from coal-derived liquids and the relative ease of their catalytic and noncatalytic conversion to oil has been found to depend upon their processing history. To facilitate chemical characterization, a simple analytical method was developed for separation of the asphaltenes into three subfractions according to their relative strength of absorption on silica gel. Using this separation technique, differences in the relative content of polar molecules were found among asphaltenes of various processing histories. In general, the relative content of polar compounds in the asphaltenes decreases with increasing conversion to oil. The relative rate of conversion also declines after the asphaltene content reaches a low level. The asphaltenes remaining after long hydrotreatment are more aromatic, contain fewer polar functional groups and are of somewhat smaller molecular size than those obtained after short hydrotreatment. The initial rates of asphaltene conversion were considerably enhanced by a commercial CoMo hydrodesulfurization catalyst. The catalyst increased the conversion of the nonpolar subfraction to a greater extent than the polar subfraction.

Activation of methane with organopalladium complexes

Abstract Selective, direct oxidation of methane to methanol is a process of scientific interest and industrial importance. Reports have appeared in the literature describing the use of organometallic complexes to effect this transformation [1–5]. Investigation of one of these reaction schemes in our laboratory has produced interesting results. Our research effort was an extension of work reported by Sen et al. [3]. The reported reaction occurs between methane (at 800 psig 5.52 MPa) and palladium(II) acetate in trifluoroacetic acid at 80°C (Eq. (1)). The product, methyl trifluoroacetate, is readily hydrolyzed to produce methanol and trifluoroacetic acid. It is reported that methyl trifluoroacetate is produced with reported conversions, calculated on palladium metal recovery, of ∼ 60 percent. CH 4 + Pd(O 2 CCH 3 ) 2 → 80° C , 800 PSIG CF 3 COOH CF 3 CO 2 CH 3 + Pd .

CARBON MONOXIDE HYDROGENATION OVER NA-MN-NI CATALYSTS : EFFECTS OF CATALYST PREPARATION METHODS ON THE C2+ OXYGENATE SELECTIVITY

Abstract The effect of catalyst preparation methods on carbon monoxide hydrogenation selectivity over na-mn-ni catalysts has been studied. the sio2-supported ni and mn-ni catalysts prepared from impregnation exhibited high methanation and hydrocarbon synthesis selectivity. the mn-ni catalysts prepared from coprecipitation of manganese and nickel nitrates with sodium carbonate showed high selectivity for c2+ oxygenate synthesis. temperature-programmed desorption studies revealed that hydrogen chemisorption on the coprecipitated catalysts was highly activated. the results suggest that highly activated hydrogen chemisorption may lead to a hydrogen-deficient surface which would favor carbon monoxide insertion relative to hydrogenation.

Photocatalytic production of methanol and hydrogen from methane and water

Abstract Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of our current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. Research in our laboratory is directed toward adapting the chemistry developed for photolysis of water to that of methane conversion. The reaction sequence of interest uses visible light, a doped tungsten oxide photocatalyst and an electron transfer molecule to produce a hydroxyl radical. Hydroxyl radical can then react with a methane molecule to produce a methyl radical. In the preferred reaction pathway, the methyl radical then reacts with an additional water molecule to produce methanol and hydrogen.

Characterization of Cu−Rh/SiO2 by temperature-programmed desorption (TPD) of hydrogen

The presence of Cu on Rh/SiO2 inhibited H2 chemisorption at 303 K and suppressed CO hydrogenation. TPD study shows that chemisorption of H2 on Cu−Rh/SiO2 is an activated process at 303 K.AbstractПрисутствие Cu на Rh/SiO2 ингибирует хемосорбцию H2 при 303 К и подавляет гидрирование CO. Результаты исследований ТПД свидетельствуют о том, что хемосорбция H2 на Cu−Rh/SiO2 является активированным процессом при температуре 303 К.

C2 oxygenates from chloromethane and carbon monoxide

Acetaldehyde (CH3CHO) and acetic acid (CH3COOH) are major products of the thermal reaction of carbon monoxide and methyl chloride under certain reaction conditions.