Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-08-31
2001-02-20
Killos, Paul J. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S780000, C528S205000
Reexamination Certificate
active
06191317
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to preparation of polyalkyl hydroxyaromatics from polyalkylenes and hydroxyaromatics. More particularly, this invention relates to production of polyalkylphenols such as polybutylphenol, from the reaction of polyalkylenes such as polybutylene with hydroxyaromatics such as phenol, in the presence of an acid catalyst and an organic solvent having a boiling point range of from at about or below the boiling point of the hydroxyaromatic to at about or above the boiling point of alkylhydroxyaromatic by-products of the reaction.
2. Description of Related Art
Polyalkyl hydroxyaromatics may be prepared by alkylating hydroxyaromatics with polymeric olefins in the presence of acidic catalysts. During such a process, some extent of depolymerization is typical, leading to the production of undesirable alkylhydroxyaromatics. For example, tert-butylphenol is an undesirable alkylphenol by-product which typically occurs during polybutene alkylation of phenol. In a typical polybutylene alkylation process, excess amounts of phenol are commonly employed to ensure good yields of polybutylphenol product. Unreacted phenol is then typically separated from polybutylphenol product and recycled to the alkylation reactor. In conventional alkylation processes, tert-butyl phenol is typically present in the phenol recycle stream. Consequently, tert-butylphenol tends to build up in the alkylation reactor, resulting in reduced yield of polybutylphenol. To maintain tert-butyl phenol content at an acceptable level within an alkylation reactor (for example less than about 2% by weight), separation is typically required. Separation of tert-butylphenol from the alkylation process stream typically requires additional process steps, costs and necessitates system downtime. Depending on the method of separation employed, substantial amounts of phenol reactant may be lost and waste product containing tert-butylphenol generated and disposed of. For example, removal of tert-butylphenol from phenol is typically accomplished by fractional distillation.
A number of processes have been developed in an attempt to address depolymerization during alkylation reactions. Such processes utilize specific catalysts and/or alkylene polymers having specific structural characteristics selected to result in reduced production of alkylhydroxyaromatics such as tert-butylphenol. However, these processes typically do not eliminate depolymerization and/or may result in reduced yields of polyalkyl hydroxyaromatic product. Furthermore, these processes may restrict catalyst selection and/or require use of specific polymer compounds having certain chemical structures.
In a typical alkylation process, excess amount of a hydroxyaromatic reactant is commonly employed to ensure good yields of polyalkyl hydroxyaromatic product. For example, in a process for alkylating phenol with polybutylene, excess phenol is typically employed. Following reaction, unreacted phenol is typically separated from the polybutylphenol product and recycled to the alkylation reactor. In a conventional process, tert-butylphenol by-product is typically present in the unreacted phenol recycle stream. Consequently, tert-butyl phenol tends to build up in the alkylation reactor, resulting in reduced yield of polybutylphenol. Because increased concentration of alkylhydroxyaromatic in the alkylation reactor results in decreased polyalkyl hydroxyaromatic yield, it is typically necessary to remove alkyl hydroxyaromatics, such as tertbutylphenol from an alkylation system on a periodic basis. Removal of alkylphenol is typically accomplished by high temperature stripping. The necessity of removing alkylphenols from an alkylation reaction system increases cost and results in down time.
In addition to the above concerns, polyalkyl hydroxyaromatic products from conventional alkylation processes are typically relatively viscous liquids that may be difficult to pump and transport.
SUMMARY OF THE INVENTION
Disclosed herein is a process for the preparation of polyalkyl hydroxyaromatics from hydroxyaromatic and polyalkylene reactants using solid acid catalyst/s. The process may employ solvent having a boiling point range with an initial boiling point less than or equal to about the boiling point of hydroxyaromatic reactant, and a final boiling point greater than or equal to about the boiling point of undesirable alkylhydroxyaromatic by-product/s associated with the reactants employed in the specific reaction. Surprisingly, utilizing a solvent having such a boiling point range, polyalkyl hydroxyaromatics may be prepared consistently, and with a minimum of downtime, from the corresponding hydroxyaromatic and polyalkylene reactants while minimizing or substantially eliminating build up of alkylhydroxyaromatic in the reaction vessel, such as may be encountered with low molecular weight/lower boiling point solvents employed in conventional alkylation processes. Instead, alkylhydroxyaromatic may be substantially absent from the reaction vessel or concentration of alkylhydroxyaromatic in the reaction vessel may reach steady state at an acceptable level. This is in contrast to conventional processes, in which lower molecular weight/lower boiling point solvents tend to distill off and be recycled with unreacted hydroxyaromatic compounds, stripping or carrying with them undesirable alkylhydroxyaromatic by-product/s, which then tend to accumulate in the reactor. Advantageously, catalyst life may be substantially unaffected using the disclosed process, and in one embodiment a catalyst may be reused for extended periods of time without regeneration.
Among other things, an organic solvent may be a mixture of aliphatic compounds and/or derivatized aliphatic compounds having a boiling point range suitable for a particular alkylation process. In one embodiment for the alkylation of phenol with polybutylene, an organic solvent employed in the preparation of polybutylphenol from phenol and polybutylene may be a mixture having a boiling point range with an initial boiling point less than the boiling point of phenol and a final boiling point at about the boiling point of tert-butylphenol. For example, such a solvent may be a mixture of paraffin and/or alkene compounds having a boiling point range lying within the overall range of from about 160° C. to about 350° C., alternatively from about 160° C. to about 300° C., alternatively from about 170° C. to about 250° C., alternatively from about 180° C. to about 210° C., alternatively from about 190° C. to about 210° C. In this embodiment, benefits of the disclosed process may be realized with organic solvents lying anywhere within these ranges, although in other embodiments the initial or minimum boiling point of such a solvent may be from about 160° C. to about 190° C., alternatively from about 160° C. to about 180° C., alternatively about 170° C.; and the final or maximum boiling point may be from about 210° C. to about 350° C., alternatively from about 210° C. to about 300° C., alternatively from about 250° C. to about 300° C., and alternatively about 250° C., it being understood that a solvent having any combination of initial and final boiling points selected from any of the respective forgoing initial and/or final boiling point ranges is possible. Such a solvent is as opposed to a solvent having, for example, a boiling point of from about 80° C. to about 100° C., as is often conventionally employed.
When employed in a polyalkyl hydroxyaromatic alkylation process which incorporates excess hydroxyaromatic and an unreacted hydroxyaromatic recycle stream, part of the disclosed organic solvent will separate from the product stream and remain with, or act as a chaser for, the recycled unreacted hydroxyaromatic. The balance of the organic solvent will remain with the polyalkyl hydroxyaromatic product stream. Advantageously, due to the boiling point range characteristics of the solvent, undesirable alkylhydroxyaromatic by-product/s tend to remain in the polyalkyl hydroxyaromatic product stream.
Huntsman Petrochemical Corporation
Killos Paul J.
O'Keefe, Egan and Peterman
Parsa J.
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