Evolution of nitrogen functionalities in carbonaceous materials during pyrolysis

Electronic structure intrinsically controls the light absorbance, redox potential, charge-carrier mobility, and consequently, photoreactivity of semiconductor photocatalysts. The conventional approach of modifying the electronic structure of a semiconductor photocatalyst for a wider absorption range by anion doping operates at the cost of reduced redox potentials and/or charge-carrier mobility, so that its photoreactivity is usually limited and some important reactions may not occur at all. Here, we report sulfur-doped graphitic C(3)N(4) (C(3)N(4-x)S(x)) with a unique electronic structure that displays an increased valence bandwidth in combination with an elevated conduction band minimum and a slightly reduced absorbance. The C(3)N(4-x)S(x) shows a photoreactivity of H(2) evolution 7.2 and 8.0 times higher than C(3)N(4) under lambda > 300 and 420 nm, respectively. More strikingly, the complete oxidation process of phenol under lambda > 400 nm can occur for sulfur-doped C(3)N(4), which is impossible for C(3)N(4) even under lambda > 300 nm. The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and, consequently, the excellent photoreactivity of C(3)N(4-x)S(x). The results acquired may shed light on general doping strategies for designing potentially efficient photocatalysts.

Unique Electronic Structure Induced High Photoreactivity of Sulfur-Doped Graphitic C3N4

Microporous activated carbon originating from coconut shell, as received or oxidized with nitric acid, is treated with melamine and urea and heated to 950 °C in an inert atmosphere to modify the carbon surface with nitrogen- and oxygen-containing groups for a systematic investigation of their combined effect on electrochemical performance in 1 M H2SO4 supercapacitors. The chemistry of the samples is characterized using elemental analysis, Boehm titration, potentiometric titration, and X-ray photoelectron spectroscopy. Sorption of nitrogen and carbon dioxide is used to determine the textural properties. The results show that the surface chemistry is affected by the type of nitrogen precursor and the specific groups present on the surface before the treatment leading to the incorporation of nitrogen. Analysis of the electrochemical behavior of urea- and melamine-treated samples reveal pseudocapacitance from both the oxygen and the nitrogen containing functional groups located in the pores larger than 10 A. On the other hand, pores between 5 A and 6 A are most effective in a double-layer formation, which correlates well with the size of hydrated ions. Although the quaternary and pyridinic-N-oxides nitrogen groups have enhancing effects on capacitance due to the positive charge, and thus an improved electron transfer at high current loads, the most important functional groups affecting energy storage performance are pyrrolic and pyridinic nitrogen along with quinone oxygen. (C)2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combined Effect of Nitrogen- and Oxygen-Containing Functional Groups of Microporous Activated Carbon on its Electrochemical Performance in Supercapacitors

The characterization of activated carbons with oxygen and nitrogen surface groups

Roles of water for chemical reactions in high-temperature water

This invention relates to novel, sulfonated terpolymers and the uses thereof. The novel, sulfonated terpolymers of the instant invention preferably have a molecular weight from 5,000 to 250,000, and are prepared by the sulfonation of a polymer obtained by the polymerization of an isoolefin, a conjugated diene, and a cyclic diolefin. The sulfonation reaction may be carried out by use of a complex of a Lewis base with a sulfur trioxide donor. The low molecular weight sulfonated polymers of the instant invention may be neutralized by reaction with inorganic or organic bases. The neutralized low molecular weight polymers of the instant invention, i.e. a molecular weight range of from 5,000 to 45,000, when combined with a plasticizer which interacts with the sulfonate group, e.g. an alcohol, show useful properties as coatings and mastics.

Sulfonated terpolymers and uses thereof

This invention provides for novel road paving binder compositions and the method of making them. One embodiment is a road paving binder composition of a storage stable blend of a sulfonated, unhydrogenated random copolymer of sytrene and butadiene having a sulfonation level of from 1 to 100 meq SO3H/100 g of polymer and a sulfonated asphalt. Another is a method of making a storage stable polymer modified asphalt composition by combining a sulfonated unhydrogenated random styrene butadiene copolymer having a sulfonation level of from about 1 to 100 meq SO3H per 100 g of polymer and a sulfonated asphalt at a temperature of at least about 180 °C to produce a storage stable polymer modified asphalt. Yet another is a method of making a storage stable polymer modified asphalt by combining a sulfonated unhydrogenated random styrene and butadiene copolymer having a sulfonation level of from about 1 to 100 meq SO3H/100 g of polymer, and unsulfonated asphalt and a basic neutralizing agent at a temperature of from about 170 °C to 185 °C to produce a storage stable polymer modified asphalt. Still another is a method for making a storage stable road paving composition by cosulfonation of a blend of unhydrogenated random styrene-butadiene copolymer and an asphalt at 180°-210 °C. The novel road paving asphaltic compositions have enhanced viscoelasticity and storage stability. The compositions can be used as binders in road paving applications. Sulfonated copolymers of random styrene-isoprene may be substituted for the sulfonated copolymers of styrene-butadiene herein.

Road paving binders

Direct Determination and Quantification of Sulfur Forms in Heavy Petroleum and Coal: Sulfur K Edge X-ray Absorption and X-ray Photoelectron Spectroscopic Approaches

There is provided a coated agricultural substrate in which the coating comprises a blend of a neutralized sulfonated ionomer and asphalt. Preferably, the coating contains from about 1 to 20 wt. % asphalt and from 99 to 80 wt. % of the neutralized sulfonated ionomer. In a particularly preferred embodiment of the present invention, the coating contains about 7 wt. % asphalt and about 93 wt. % of the neutralized sulfonated ionomer.

Sustained release agricultural substrate coated with a blend of EPDM and asphalt

A process for the treatment of a calcium-containing subbituminous coal and coals of lower rank to form insoluble, thermally stable calcium salts which remain within the solids portions of the residue on liquefaction of the coal, thereby suppressing the formation scale, made up largely of calcium carbonate deposits, e.g., vaterite, which normally forms within the coal liquefaction reactor (i.e., coal liquefaction zone), e.g., on reactor surfaces, lines, auxiliary equipment and the like. A solution of a compound or salt characterized by the formula MX, where M is a Group IA metal of the Periodic Table of the Elements, and X is an anion which is capable of forming water-insoluble, thermally stable calcium compounds, is maintained in contact with a particulate coal feed sufficient to impregnate said salt or compound into the pores of the coal. On separation of the impregnated particulate coal from the solution, the coal can be liquefied in a coal liquefaction reactor (reaction zone) at coal liquefaction conditions without significant formation of vaterite or other forms of calcium carbonate on reactor surfaces, auxiliary equipment and the like; and the Group IA metal which remains within the liquefaction bottoms catalyzes the reaction when the liquefaction bottoms are subjected to a gasification reaction.

Martin L. Gorbaty

Papers

Sulfonated terpolymers and uses thereof

Road paving binders

Direct Determination and Quantification of Sulfur Forms in Heavy Petroleum and Coal: Sulfur K Edge X-ray Absorption and X-ray Photoelectron Spectroscopic Approaches

Sustained release agricultural substrate coated with a blend of EPDM and asphalt

Liquefaction of calcium-containing subbituminous coals and coals of lower rank