Keywords

Piperylene, Chemistry, Technical, Polymerization, Polymers

Abstract

Piperylene concentrate is a complex mixture of 5-carbon unsaturated hydrocarbons obtained as a by-product when naphtha or gas oils are cracked. The major component in this mixture is 1,3-pentadiene. During the course of this study, a number of trials, utilizing liquid phase reaction conditions, were made to investigate the geometric isomerization of 1,3-pentadiene and its separation from the piperylene concentrate. Isomerization was accomplished employing catalytic amounts of iodine at temperatures ranging from 0°C to reflux. Using this method, the maximum amount of trans-1,3-pentadiene obtained was 70% as compared to 51% in the piperylene concentrate. Recovery of the product was 90%, with the remainder being diiodo compounds and polymer. Isomerizations employing catalytic amounts of potassium tert-butoxide were also investigated. Using this anionic isomerization, the theoretical amount of trans-1,3-pentadiene (84% @ 20°C) was obtained in the product. The greatest drawback with this technique was the low recover (50%), due to the extensive polymer formation. Successful separation of 1,3-pentadiene from the mixture was accomplished through cuprous chloride complexing. Utilizing this technique, 54% of the 1,3-pentadiene was recovered from the mixture, with the separated product being 99.9% pure 1,3-pentadiene. Separation of trans-1,3-pentadiene from the mixture was accomplished through a Diels-Alder reaction with maleic anhydride. Since this dienophile will react readily with trans-1,3-pentadiene but not cis-1,3-pentadiene, this method offered an easy and efficient means of removing the former isomer from the mixture. In attempting to reverse this Diels-Alder, via pyrolysis, many products were obtained; including those present in the original mixture. The gas phase dehydrocyclization of 1,3-pentadiene was investigated in a 316 stainless steel tubular flow reactor utilizing various heterogeneous and homogeneous catalysts. The selectivity to cyclopentadiene was greatest (60%) in the presence of a hydrogen sulfide promoter. For all other catalysts, the selectivity remained relatively constant (30%). This constant selectivity over a wide range of parameters indicates that a significant amount of competing side reactions are prevailing within the preheater section of the apparatus.

Notes

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Graduation Date

Summer 1979

Advisor

Mattson, Guy C.

Degree

Master of Science (M.S.)

College

College of Natural Sciences

Degree Program

Industrial Chemistry

Format

PDF

Pages

ix, 99 pages

Language

English

Rights

Public Domain

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0013223

Subjects

Piperylene, Chemistry, Technical, Polymerization, Polymers

Collection (Linked data)

Retrospective Theses and Dissertations

Included in

Chemistry Commons

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