Abstract: A system for mixing ortho-xylene with an oxygen-containing gas such as air comprises an evaporator vessel fed with the gas and having a lance projecting into the gas. The lance is provided with a metal spray nozzle for injecting droplets of hot liquid ortho-xylene into the gas stream, concurrently with the direction of flow of the gas. The metal at the surface of the spray nozzle, that in use is in contact with the liquid ortho-xylene, has a high surface hardness to resist erosion, particularly by cavitation. The system is useful in the production of phthalic anhydride by the oxidation of ortho-xylene with air, whereby the risk for deflagrations is reduced. A soft metal seal is the preferred gasket between the spray nozzle and the lance.

Abstract: A process for producing esters comprises esterifying an acid or anhydride with an excess of an alcohol to produce a crude ester, recovering excess alcohol from the crude ester and recycling recovered excess alcohol to the esterification reaction together with fresh alcohol. The process is improved by controlling the ratio of the amount of recycled alcohol and the amount of fresh alcohol in dependence on the level of impurities in the recycle alcohol. Further improvements come from feed forwarding fresh alcohol analysis results and from preheating the alcohol before loading into the reactor. Preferably, ester product quality is improved by stripping the alcohol for oxygen removal prior to esterification.

Abstract: Esters produced by the catalyzed reaction of alcohols and acids or anhydrides are neutralized by treatment with an aqueous alkaline alkali metal salt solution in an amount that provides less than a stoichiometric amount of alkali metal salt in relation to the acidity of the crude ester and the amount of water present during the treatment is from 0.8 to 1.4 wt % of water based on the weight of crude ester. When using titanium as the esterification catalyst, the ester resulting from this process contains less than 0.01 ppm by weight of titanium residue, so that it is storage stable when stored in the presence of an antioxidant.

Abstract: A method for performing a flying grade switch in an ester production process, which preferably is operated in semi-continuous mode, maximizes plant equipment productivity while minimizing product cross-contamination. Mixed ester products of the process containing a C9-C11 alkyl or isodecyl benzoate together with a higher molecular weight di-alkyl phthalate or cyclohexanoate, bring performance advantages such as improved permanence in plasticized PVC articles or improved processability in manufacturing these articles.

Abstract: In the production of phthalic anhydride by the oxidation of ortho-xylene with air, the ortho-xylene loading is increased without increasing the likelihood of explosion by insulating the system to avoid cold spots to keep the ortho-xylene at a temperature above its dew point; in addition the system may be electrically interconnected and grounded to reduce the risk of spark initiated explosions or deflagrations.

Abstract: The efficiency of catalyzed batch esterification reactions is improved by the use of a particular temperature and pressure profile during the reaction cycle. In particular elevated pressure is maintained to prevent alcohol boil off during initial mixing and reaction of the reactants prior to any catalyst addition, and preferably the pressure is reduced rapidly after the desired reaction temperature has been reached.

Abstract: In the production of phthalic anhydride by the oxidation of ortho-xylene with air, the ortho-xylene loading is increased without increasing the likelihood of explosion by insulating the system to avoid cold spots to keep the ortho-xylene at a temperature above its dew point; in addition the system may be electrically interconnected and grounded to reduce the risk of spark initiated explosions or deflagrations.

Abstract: A system for mixing ortho-xylene with an oxygen-containing gas such as air comprises an evaporator vessel fed with the gas and having a lance projecting into the gas. The lance is provided with a metal spray nozzle for injecting droplets of hot liquid ortho-xylene into the gas stream, concurrently with the direction of flow of the gas. The metal at the surface of the spray nozzle, that in use is in contact with the liquid ortho-xylene, has a high surface hardness to resist erosion, particularly by cavitation. The system is useful in the production of phthalic anhydride by the oxidation of ortho-xylene with air, whereby the risk for deflagrations is reduced. A soft metal seal is the preferred gasket between the spray nozzle and the lance.

Abstract: The efficiency of catalysed batch esterification reactions is improved by the use of a particular temperature and pressure profile during the reaction cycle. In particular elevated pressure is maintained to prevent alcohol boil off during initial mixing and reaction of the reactants prior to any catalyst addition, and preferably the pressure is reduced rapidly after the desired reaction temperature has been reached.

Abstract: A process for producing esters comprises esterifying an acid or anhydride with an excess of an alcohol to produce a crude ester, recovering excess alcohol from the crude ester and recycling recovered excess alcohol to the esterification reaction together with fresh alcohol. The process is improved by controlling the ratio of the amount of recycled alcohol and the amount of fresh alcohol in dependence on the level of impurities in the recycle alcohol. Further improvements come from feed forwarding fresh alcohol analysis results and from preheating the alcohol before loading into the reactor. Preferably, ester product quality is improved by stripping the alcohol for oxygen removal prior to esterification.

Abstract: A method for performing a flying grade switch in an ester production process, which preferably is operated in semi-continuous mode, maximises plant equipment productivity while minimizing product cross-contamination. Mixed ester products of the process containing a C9-C11 alkyl or isodecyl benzoate together with a higher molecular weight di-alkyl phthalate or cyclohexanoate, bring performance advantages such as improved permanence in plasticised PVC articles or improved processability in manufacturing these articles.

Abstract: Esters produced by the catalyzed reaction of alcohols and acids or anhydrides are neutralized by treatment with an aqueous alkaline alkali metal salt solution in an amount that provides less than a stoichiometric amount of alkali metal salt in relation to the acidity of the crude ester and the amount of water present during the treatment is from 0.8 to 1.4 wt % of water based on the weight of crude ester. When using titanium as the esterification catalyst, the ester resulting from this process contains less than 0.01 ppm by weight of titanium residue, so that it is storage stable when stored in the presence of an antioxidant.