Abstract: Methods and compositions are provided for inhibiting the polymerization of a vinyl aromatic monomer, such as styrene monomer, during elevated temperature processing or distillation thereof or during storage or shipment of polymer containing product. The compositions include a combination of a hydroxybenzyl alcohol (1) and a dehydration catalyst (2). The combination is added to a vinyl aromatic monomer. Typically, the hydroxybenzyl alcohol is dehydrated in the styrene solution by the use of a strong acid catalyst acting as the dehydration catalyst, and the resultant reaction product is a quinone methide styrene inhibitor.

Abstract: Methods and compositions are provided for inhibiting the polymerization of a vinyl aromatic monomer, such as styrene monomer, during elevated temperature processing thereof or during storage or shipment of polymer containing product. The compositions comprise a combination of a quinone methide derivative A) and a phenol compound B). The methods comprise adding from about 1-10,000 ppm of the combination to the monomer containing medium, per one million parts of the monomer.

Abstract: The present invention includes methods for improving the operational parameters in primary fractionators which are experiencing diminished operation efficiencies due to deposits of polymerized hydrocarbon species. The invention comprises the step of adding a foam reducing amount of a foam reducing composition at the primary fractionator. A reduction in foaming is achieved whereby the operational efficiency of the process is improved based upon operation parameters including, but not limited to, liquid-gas contact ratio, product top temperature, pressure differentials, gasoline end point or combinations thereof.

Abstract: Described is a method for operating and shutting down a dehydrogenation reactor that contains a volume of dehydrogenation catalyst. After termination of the introduction of a dehydrogenation feed into the dehydrogenation reactor that is operated under dehydrogenation reaction conditions, a first cooling fluid comprising steam is introduced into the reactor for a first time period sufficient to cool the dehydrogenation catalyst contained in the dehydrogenation reactor to a second temperature. The introduction of the first cooling fluid is terminated followed by the introduction of a second cooling fluid for a second time period sufficient to cool the dehydrogenation catalyst contained in the dehydrogenation reactor to a third temperature that allows for the handling and removal of the dehydrogenation catalyst from the dehydrogenation reactor.

Abstract: Improved methods for conducting solid acid-catalyzed, near- or supercritical heterogeneous chemical reactions (e.g., alkylation reactions) are provided which give enhanced product yields and permit longer processing runs. The preferred reactions of the invention are carried out in the presence of a solid macroporous catalyst having a surface area of from about 50-400 m2/g and a pore size of from about 70-150 ?. Product selectivity is enhanced by pressure-tuning of the reaction to promote production and separation of desired reaction products. In continuous processing, the chemical reaction may be interrupted before significant catalyst deactivation, followed by increasing reactor pressure and/or reducing reactor temperature to remove the accumulating coke; when the catalyst is regenerated, the original reaction conditions and reactant introduction may be resumed.

Abstract: The polymerization of a vinylaromatic or vinylaliphatic compound at elevated temperature in the absence of air is inhibited by processing the vinylaromatic or vinylaliphatic compound in the presence of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl or 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxylalone or in admixture with p-nitrosophenol or 2-methyl-4-nitrosophenol.

Abstract: Applicants have developed a process for inhibiting the polymerization of vinyl aromatic compound during the distillation of the vinyl aromatic compounds. The process involves adding to the vinyl aromatic compound, e.g., styrene, a nitroso compound such as N-nitroso-N, N'-di-3-pentyl-p-phenylenediamine.

Abstract: A method for inhibiting fouling during the elevated temperature processing of hydrocarbon comprising adding to the hydrocarbon a composition comprising a catechol having the structure: ##STR1## wherein R is H or C.sub.1 -C.sub.10 alkyl and, an organic acid.

Abstract: A process for stabilizing vinyl monomers in general, and ar-brominated styrene polymer in particular, against polymerization by mixing a vinyl monomer such as an ar-brominated styrene monomer with a stabilizing amount of iodine composition to produce a stabilized monomer and novel stabilized compositions.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of a N,N-dialkylhydroxylamine and an alkyl benzene sulfonic acid.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of mixtures of alkyl-substituted p-nitrosophenols and p-nitrosophenol.

Abstract: Hydrocarbon processing equipment is protected against fouling during the processing of hydrocarbons at elevated temperatures by adding to the equipment small amounts of the N,N'-dimer of phenothiazine or a substituted phenothiazine.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of at least one N,N' dimer of phenothiazine or a substituted phenothiazine and at least one mono- or ditertiary alkylphenol.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of at least one N,N' dimer of phenothiazine or a substituted phenothiazine and at least one mono- or ditertiary alkyl catechol and/or at least one mono- or ditertiary alkylhydroquinone.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of at least one N,N-diarylhydroxylamine and at least one N,N' dimer of phenothiazine or substituted phenothiazine.

Abstract: Vinyl aromatic compounds are stabilized against undesired polymerization by adding to the vinyl aromatic compounds small amounts of the N,N'-dimer of phenothiazine or a substituted phenothiazine.

Abstract: A process for distilling vinyltoluene comprising subjecting vinyltoluene to distillation conditions in the presence of a synergistic polymerization inhibiting mixture of N-nitrosodiphenylamine (NDPA) and dinitro-para-cresol (DNPC). Preferably from about 100 to about 300 ppm by weight NDPA and about 300 to about 700 ppm by weight DNPC are dissolved in the crude vinyltoluene and the resulting solution is vacuum distilled.

Abstract: A method of inhibiting the polymerization of styrene which comprises mixing with the styrene a minor but effective quantity of an inhibitor compound selected from the group consisting of 2-methylbenzoquinone-4-oxime, 2,3,5-trimethylbenzoquinone-4-oxime and mixtures thereof.

Abstract: Disclosed is a method for preventing the polymerization of a readily polymerizable vinyl aromatic compound during distillation at elevated temperatures within a distillation apparatus which is subject to an emergency condition, such as a power outage. This method comprises force feeding a supplemental polymerization inhibitor having a high solubility in the vinyl aromatic compound, and a long duration of efficiency, into each of the distillation vessels of a conventional distillation apparatus in an amount sufficient to prevent polymerization therein. In the preferred embodiment the supplemental polymerization inhibitor comprises 2,6-dinitro-p-cresol and meta-nitro-para-cresol.

Abstract: A method for reducing losses due to reactions between hydrogen halides and olefinically unsaturated organic compounds in the presence of transition metals which act as catalysts for hydrohalogenation in mixtures containing same by adding to said mixtures a compound selected from the class consisting of alkyl diketones. The present invention is of particular value in the separation of components of said mixtures by distillation, but may also be usefully employed in any operation in which these mixtures are maintained in the presence of said catalytic materials. The present method offers advantages over the prior art because of the relative low toxicity and flammability of diketones and the fact that no undesirable solids are formed to foul process equipment as with some known methods.