Membrane-based gas separation

A method for applying a digital watermark to a content signal is disclosed. In accordance with such a method, a watermarking key is identified. The watermarking key includes a binary sequence and information describing application of that binary sequence to the content signal. The digital watermark is then encoded within the content signal at one or more locations determined by the watermarking key.

Method and system for digital watermarking

A membrane for gas separation or pervaporation. The membrane is a composite of a microporous support membrane and an ultrathin permselective membrane, the permselective membrane being made from a polyamide-polyether block copolymer having the general form: ##STR1## where PA is a saturated aliphatic polyamide segment, PE is a polyether segment, and n is a positive integer. The membrane is particularly useful in separating polar gases from non-polar gases.

Composite membrane, method of preparation and use

An energy efficient desalination process that does not produce waste products involves the extraction of water from a first solution, such as seawater, by using a second concentrated solution to draw the water from the first solution across a semi-permeable membrane. By manipulating the equilibrium of the soluble and insoluble species of solute within the second solution in favor of the soluble species of the solute, a saturated second solution can be used to generate osmotic pressure on the first solution. Also, by adjusting the equilibrium in favor of the less soluble species after the water has been drawn from the first solution, a portion of the solute can easily be precipitated out. Heating the second solution decomposes the solute into its constituent gases. The constituent gases and precipitated solute may be recycled through the process to affect the changes in equilibrium and eliminate waste products. Additionally, by using the waste steam from industrial sources and a heat pump to effectively distribute heat through the present method, the present method exhibits greater energy efficiency than prior art methods.

Osmotic desalination process

A membrane process for the removal of sulfur species from a naphtha feed, in particular, a FCC light cat naphtha, without a substantial loss of olefin yield is disclosed. The process involves contacting a naphtha feed stream with a membrane having sufficient flux and selectivity to separate a sulfur deficient retentate fraction from a sulfur enriched permeate fraction, preferably, under pervaporation conditions. Sulfur deficient retentate fractions are useful directly into the gasoline pool. Sulfur-enriched permeate fractions are rich in sulfur containing aromatic and nonaromatic hydrocarbons and are further treated with conventional sulfur removal technologies, e.g. hydrotreating, to reduce sulfur content. The process of the invention provides high quality naphtha products having a reduced sulfur content and a high content of olefin compounds.

Membrane separation for sulfur reduction

A method was developed to measure the active centers in a titanium tetrachloridealkylaluminum catalyst system for the polymerization of ethylene. The method depends on the assertion that the active carbon atom of the growing chain is relatively basic and will react with alcohol-O-t. The tritium becomes incorporated in the polymer. The relationship used is N = AG/a, where N is the corrected active center concentration, A is the radioactivity of the polyethylene in counts/min./g., G is the polymer concentration at the time of sampling and a is the specific activity of the quench methanol-O-t in counts/min./mole. The data were corrected for the kH/kT isotope effect of 3.7 which was measured for the alcohol-O-t reaction. This isotope effect was unchanged over a wide range of molecular weights and reaction conditions. The basicity of the carbon on the growing polymer chain was proved by quenching the reaction with C14-labelled alcohol. The resulting polymer was not radioactive. The values of N could be correlated with polymerization rates. Values of the active center concentration and polymer chain lifetime were calculated as a function of molecular weight using fractionated polymer. The centers are very heterogeneous and the lifetimes of polymer chains range from 1 to 30 min. (with an average of 4 min. for the particular conditions used). Calculated values of viscosity- (Mv) and number-average molecular weights as a function of time of reaction agreed well with the experimental data. Because of the long lifetime of some chains, a steady state in Mv is not reached, and Mv increases throughout the course of the reaction. Catalyst efficiency was calculated from a knowledge of N. The efficiency, which can vary from 0.3 to 15% based on the titanium, is a function of how the catalyst components are brought together. The value of N in these systems is about 10−3 to 10−4 moles/liter compared to 10−7 to 10−9 for the concentration of active species in free radical systems. The value of the propagation constant, kp, is comparable in both systems. It is concluded that the very rapid polymerization rate in these heterogeneous systems is due solely to high values of N. These high values of N argue against bimolecular termination of centers. The stability of the centers when refluxed under argon support this idea and cast doubt on chain termination via hydride ion transfer or transfer to solvent. The value for the activation energy of kp is 11.8 over the range of 40 to 68°C. The value of the activation energy for initiation of centers is deduced to be 11.8 kcal./mole, also.

Active centers in the polymerization of ethylene using titanium tetrachloride–alkylaluminum catalysts

Organics are separated from aqueous solutions by contacting the aqueous solution feed with a first surface of a polymeric membrane selectively permeable to organic components; while maintaining a second and opposite membrane surface at a lower chemical potential than the first membrane surface for said organic components, permeating a portion of the organic components into and through the membrane; and withdrawing from the second membrane surface a mixture having a higher total concentration of organic components than the organic components concentration of the aqueous solution feed stream.

Membrane separation of organics from aqueous solutions

Process for the separation of water from mixtures of water and formaldehyde, by contacting the mixtures against an organic polymeric membrane, and withdrawing at the other side of the membrane a mixture having a higher concentration of water.

Process for separating aqueous formaldehyde mixtures

Dienes are separated from organic mixtures comprising diene and alkene having one double bond by contacting the mixture against one side of a glycidyl methacrylate polymer membrane and withdrawing at the other side a vaporous mixture having increased diene concentration. Exemplary of the organic mixtures is a mixture of butadiene and butene.

Process for the separation of diene from organic mixtures

Ammonia synthesis processes are disclosed which provide enhanced conversion of hydrogen values to ammonia. In the processes, a purge stream from an ammonia synthesis loop, which purge stream contains ammonia, is contacted at a superatmospheric pressure with the feed side of a separation membrane which exhibits selective permeation of each of hydrogen and ammonia as compared to the permeation of each of methane and argon. A total pressure differential across the membrane is maintained to provide a driving force for the permeation of hydrogen and ammonia through the membrane. A hydrogen-rich permeating gas which contains ammonia is obtained on the permeate exit side of the membrane. The permeating gas is combined with the gas in the ammonia synthesis loop and passed to the ammonia synthesis reaction zone for conversion to ammonia. Ammonia which permeates the membrane can be recovered by the means to remove product ammonia from the gas in the synthesis loop. A non-permeating gas is removed from the feed side of the separation membrane at substantially the same pressure at which the purge stream is contacted with the separation membrane.

Eli Perry

Papers

Active centers in the polymerization of ethylene using titanium tetrachloride–alkylaluminum catalysts

Membrane separation of organics from aqueous solutions

Process for separating aqueous formaldehyde mixtures

Process for the separation of diene from organic mixtures

Process for hydrogen recovery from ammonia purge gases