Integrated plants and associated processes for producing ammonia and sulfuric acid have been developed comprising air separation and water electrolysis subsystems and which make surprisingly efficient use of the products from these subsystems (i.e. oxygen and nitrogen from the former and hydrogen and oxygen from the latter). The invention is particularly suitable for use as part of an integrated fertilizer production plant.

Methods are disclosed for forming a Silicon Metal Oxide film using a mono-substituted TSA precursor. The precursors have the formula: (SiH3)2N—SiH2-X, wherein X is selected from a halogen atom; an isocyanato group; an amino group; an N-containing C4-C10 saturated or unsaturated heterocycle; or an alkoxy group.

Methods are disclosed for forming a Silicon Metal Oxide film using a mono-substituted TSA precursor. The precursors have the formula: (SiH3)2N—SiH2-X, wherein X is selected from a halogen atom; an isocyanato group; an amino group; an N-containing C4-C10 saturated or unsaturated heterocycle; or an alkoxy group.

Systems and processes for gas phase-phase synthesis of trisilylamine. One system includes a reactor vessel having a top, bottom, and sidewall having an inner surface. The reactor vessel includes inlets for gaseous reactants, and a gas inlet for an inert gas. In certain reactors the gas inlets are positioned near the top of the reactor vessel and configured to inject the reactant gases in the reactor substantially vertically and downward therefrom. Other reactors are cyclonic-shaped with tangential feeding of the gases. One or more baffles having a peripheral edge and substantially horizontally positioned in the reactor to define a reaction zone above the baffles and a separation zone below the baffles. The baffles are positioned in the reactor vessel such that there is a gap between the baffle peripheral edge and the inner surface of the reactor vessel. Certain systems and processes include mechanical or static mixers.

Systems and processes for gas phase-phase synthesis of trisilylamine. One system includes a reactor vessel having a top, bottom, and sidewall having an inner surface. The reactor vessel includes inlets for gaseous reactants, and a gas inlet for an inert gas. In certain reactors the gas inlets are positioned near the top of the reactor vessel and configured to inject the reactant gases in the reactor substantially vertically and downward therefrom. Other reactors are cyclonic-shaped with tangential feeding of the gases. One or more baffles having a peripheral edge and substantially horizontally positioned in the reactor to define a reaction zone above the baffles and a separation zone below the baffles. The baffles are positioned in the reactor vessel such that there is a gap between the baffle peripheral edge and the inner surface of the reactor vessel. Certain systems and processes include mechanical or static mixers.

[Problem] To provide a perhydropolysilazane making it possible to form a siliceous film with minimal defects, and a curing composition comprising the perhydropolysilazane. [Means for Solution] The present invention provides a perhydropolysilazane having a weight-average molecular weight of 5,000 to 17,000, characterized in that when .sup.1H-NMR of a 17% by weight solution of said perhydropolysilazane dissolved in xylol is measured, the ratio of the amount of SiH.sub.1,2 based on the aromatic ring hydrogen content of the xylol is 0.235 or less and the ratio of the amount of NH based on the aromatic ring hydrogen content of the xylol is 0.055 or less, and a curing composition comprising the perhydropolysilazane. The present invention also provides a method for forming a siliceous film, comprising coating the curing composition on a substrate and heating.

[Problem] To provide a perhydropolysilazane making it possible to form a siliceous film with minimal defects, and a curing composition comprising the perhydropolysilazane. [Means for Solution] The present invention provides a perhydropolysilazane having a weight-average molecular weight of 5,000 to 17,000, characterized in that when .sup.1H-NMR of a 17% by weight solution of said perhydropolysilazane dissolved in xylol is measured, the ratio of the amount of SiH.sub.1,2 based on the aromatic ring hydrogen content of the xylol is 0.235 or less and the ratio of the amount of NH based on the aromatic ring hydrogen content of the xylol is 0.055 or less, and a curing composition comprising the perhydropolysilazane. The present invention also provides a method for forming a siliceous film, comprising coating the curing composition on a substrate and heating.

An economical method for recovering phosphate or phosphate and nitrogen from liquid streams. A liquid containing phosphate is introduced into a culture of autotrophic microorganisms in the presence of natural or artificial light, thereby producing a liquid effluent with elevated pH and reduced alkalinity. The alkalinity is reduced through the consumption of bicarbonate/carbonate by the autotrophic microorganisms. The effluent is then chemically treated with low-cost chemicals to provide Ca.sup.++ or Mg.sup.++ ions necessary to form a phosphate precipitate such as calcium phosphate or magnesium-ammonium-phosphate (MAP). The autotrophic microorganisms can be cultivated in ponds, lagoons, or photobioreactors. The pH of the culture is adjustable within a preferred range of 7.5 to 10.5 by adjusting the photobioreactor operation. The process includes an economical flotation separator for solid, liquid, gas separation and a means of concentrating ammonia nitrogen that may also be removed during the process of phosphate reclamation.

An economical method for recovering phosphate or phosphate and nitrogen from liquid streams. A liquid containing phosphate is introduced into a culture of autotrophic microorganisms in the presence of natural or artificial light, thereby producing a liquid effluent with elevated pH and reduced alkalinity. The alkalinity is reduced through the consumption of bicarbonate/carbonate by the autotrophic microorganisms. The effluent is then chemically treated with low-cost chemicals to provide Ca.sup.++ or Mg.sup.++ ions necessary to form a phosphate precipitate such as calcium phosphate or magnesium-ammonium-phosphate (MAP). The autotrophic microorganisms can be cultivated in ponds, lagoons, or photobioreactors. The pH of the culture is adjustable within a preferred range of 7.5 to 10.5 by adjusting the photobioreactor operation. The process includes an economical flotation separator for solid, liquid, gas separation and a means of concentrating ammonia nitrogen that may also be removed during the process of phosphate reclamation.

Mono-substituted TSA precursor Si-containing film forming compositions are disclosed. The precursors have the formula: (SiH.sub.3).sub.2N—SiH.sub.2—X, wherein X is selected from a halogen atom; an isocyanato group; an amino group; an N-containing C.sub.4-C.sub.10 saturated or unsaturated heterocycle; or an alkoxy group. Methods for forming the Si-containing film using the disclosed mono-substituted TSA precursor are also disclosed.