John W. Otvos

Plant crops as a source of fuel and hydrocarbon-like materials.

Chemical analyses have been made of a number of plant species in order to assess their suitability as renewable sources of hydrocarbon-like photosynthetic products. Yields of rubber and wax, glycerides, isoprenoids, and other terpenoids were estimated. Individual sterols were identified in latex from some species.

Liquid fuels fromMesua ferrea L. seed oil

Mesua ferrea L. seed oil consists of triglycerides of linoleic, oleic, palmitic and stearic acids. These acids were pyrolyzed separately in the presence of different amounts of solid sodium carbonate. Pyrolysis experiments revealed that linoleic and oleic acids can be converted to hydrocarbons of a wide range of molecular weights by pyrolyzing them with even 1% by wt of sodium carbonate up to a temperature of 500°C, whereas palmitic and stearic acids can be converted to hydrocarbons only by pyrolyzing them with equivalent amounts or more of sodium carbonate up to a temperature of about 650°C.The fractions of boiling range 60–320°C of all of the pyrolytic oils were analyzed for their hydrocarbon types by the method of fluorescent indicator adsorption (FIA). The aromatic contents of the pyrolytic oils of linoleic and oleic acids were found to be much higher than those of palmitic and stearic acids. GS and GC-MS analyses of all the saturate fractions indicated mainly normal alkanes with a carbon number range of 6 to 17.

ANALYSIS OF EXTRACTABLES FROM ONE EUPHORBIA

Chemical analyses have been made of the heptane extractable material ofEuphorbia lathyris, a plant which has been proposed as an “energy farm” candidate. The heptane extract is 4–5% of the dry plant weight and has a heat value of ≈18×103 BTU/Ib. This reduced photosynthetic material consists almost entirely of polycyclic triterpenoids.

Plants as a direct source of fuel

Euphorbia lathyris, a plant which has been proposed as an ‘energy farm’ candidate yields a total of 35% of its dry weight as simple organic extractables. Chemical analyses of the extracts show that 5% of the dry weight is a mixture of reduced terpenoids, in the form of triterpenoids, and 20% of the dry weight is simple sugars in the form of hexoses. The terpenoids can be converted to a gasoline-like substance and the sugars can be fermented to alcohol. Based on a biomass yield of about 25 dry tons ha−1 year−1, the total energy that can be obtained from this plant in the form of liquid fuels is 48 MJ ha−1 year−1, 26 MJ in the form of hydrocarbons and 22 MJ in the form of ethanol. A conceptual process study for the large scale recovery ofEuphorbia lathyris products indicates that this crop is a net energy producer. Several lines of investigation have been started to increase the hydrocarbon yield of this plant. Tissue cultures ofE. lathyris have been established and will be used for selection, with the aim of regenerating a superior plant. Biochemical studies have been initiated to elucidate regulation of terpenoid metabolism. Future plans include eventual genetic engineering to select the most desirable plant for hydrocarbon production.

Photoeffects in Fe2O3 sintered semiconductors

Polycrystalline sintered pellets of ..cap alpha..-Fe/sub 2/O/sub 3/ have been studied by capacitance and photoelectrochemical techniques. The pellets exhibit (i) photocurrent saturation at a given wavelength with increasing applied voltage, (ii) large dark currents at low applied voltage (0.76 ..mu..A cm/sup -2/ at +0.2 V SCE), (iii) cathodic and anodic photocurrent transients at low levels of monochromatic irradiation, (iv) photocurrent onset at photon energies greater than 2.1 eV, and (v) flat-band potentials of -0.67 V SCE and pH=4. Capacitance measurements followed a Mott-Schottky relationship indicating a predominance of the semiconductor space-charge layer over surface states and electrolyte effects. No degradation of the semiconductor properties could be observed at pH=4.

Photoeffects in Fe/sub 2/O/sub 3/ sintered semiconductors

Polycrystalline sintered pellets of ..cap alpha..-Fe/sub 2/O/sub 3/ have been studied by capacitance and photoelectrochemical techniques. The pellets exhibit (i) photocurrent saturation at a given wavelength with increasing applied voltage, (ii) large dark currents at low applied voltage (0.76 ..mu..A cm/sup -2/ at +0.2 V SCE), (iii) cathodic and anodic photocurrent transients at low levels of monochromatic irradiation, (iv) photocurrent onset at photon energies greater than 2.1 eV, and (v) flat-band potentials of -0.67 V SCE and pH=4. Capacitance measurements followed a Mott-Schottky relationship indicating a predominance of the semiconductor space-charge layer over surface states and electrolyte effects. No degradation of the semiconductor properties could be observed at pH=4.

Photosensitized electron transfer reactions in organized interfacial systems

Abstract The separation of photoproducts formed in photosensitized electron transfer reactions is essential for efficient energy conversion and storage. The organization of the components involved in the photoinduced process in interfacial systems leads to efficient compartmentalization of the products. Several interfacial systems, e.g. lipid bilayer membranes (vesicles), water-in-oil microemulsions and a solid SiO 2 colloidal interface, were designed to accomplish this goal. An electron transfer across a lipid bilayer membrane leading to the separation of the photoproducts at opposite sides of the membrane is facilitated by establishing a transmembrane potential and organizing the cotransport of cations with specific carriers. Colloidal SiO 2 particles provide a charged interface that interacts with charged photoproducts. By designing a system that results in oppositely charged photoproducts, a retardation of recombination by the charged interface can be produced. The photosensitized reduction of a neutral acceptor by positively charged sensitizers is described. The reactions are substantially enhanced in the SiO 2 colloid compared with in the homogeneous phase. The effect of the SiO 2 interface is attributed to a high surface potential that results in the separation of the intermediate photoproducts. The quantum yields of the photosensitized reactions are correlated with the interfacial surface potential and the electrical effects of other charged interfaces such as micelles are compared with those of SiO 2 . The possible utilization of the energy stored in the stabilized photoproducts in further chemical reactions is discussed. Special attention is given to the photodecomposition of water.

Synthesis and properties of two bimetallic mixed-valence di-µ-oxo manganese complexes with different tetra-aza macrocyclic ligands

Mixed-valence di-µ-oxo complexes of the form [LMnO]2(ClO4)3(L = 1,4,8,11-tetra-azacyclotetradecane or 1,4,7,10-tetra-azacyclododecane) have been synthesized; their electrochemical properties in 1.5% water–acetonitrile indicate that the oxidized forms interact with water.

A Novel Conformation for a Coordinated Macrocycle: The Crystal Structure of [Ni(12-aneN4)(OH2)2](CIO4)2·H2O; (12-aneN4 = 1,4,7,10-Tetraazacyclododecane)

Abstract The complex [Ni(12-aneN4)(OH2)2](ClO4)2·H2O (12-aneN4 = 1,4,7,10-tetraazacyclododecane) has been prepared and its structure determined. The complex crystallizes in the orthorhombic space group P212121 With a= 11.173(5), b = 11.976(5) and c = 13.969(4) A. The volume of the unit cell is 1869(1) A3. The total reflections collected for 2.0 ≤ 20 ≤ 50.0° were 1916 with 1895 being unique and 1659 used in the structure determination. Final values of R = 0.053 and R w = 0.057 were obtained. Our results indicate that this six coordinate Ni(II) species has a cis or folded geometry and that the coordinated tetraazamacrocyclic ligand exhibits a conformation that is unprecedented in the literature. In this new conformation three of the hydrogens coordinated to the nitrogens point towards the metal centre while only one hydrogen coordinated to a nitrogen points away from the metal centre.

PREPARATION OF OXOPORPHINATOMANGANESE (IV) COMPLEX

Oxo-manganese-tetraphenylporphyrin (O=Mn{sup IV}-TPP) has been prepared by an oxygen-transfer reaction from iodosylbenzene to MnIITPP and characterized by its i.r. and field desorption mass spectra, which are identical to those of the product obtained by direct oxidation of Mn{sup III}(TPP) in an aqueous medium; it transfers oxygen to triphenylphosphine to produce triphenylphosphine oxide, and it is suggested that similar intermediates are important in oxygen activation by cytochrome P-450 as well as in the photosynthetic evolution of oxygen.