Published online by Cambridge University Press: 15 September 2022
Terephthalic acid (TPA) is a commodity chemical made by treating p-xylene (pX) with oxygen (O2) via the so-called Mid-Century (MC) process. TPA is a key ingredient to make polyethylene terephthalate plastic used in water bottles. The MC process uses a stirred reactor in which O2 is dispersed through an acetic acid solution of pX and catalyst (Co/Mn/Br). However, O2 starvation in the liquid phase causes incomplete oxidation necessitating product purification in a catalytic hydrogenation unit that accounts for nearly 50%, 16% and 33% of the overall capital investment, operating costs and greenhouse gas emissions, respectively. To mitigate O2 starvation, an alternate reactor technology is presented wherein the continuous and dispersed phases are reversed by spraying the liquid phase as fine droplets into a vapor phase containing O2 to increase the gas–liquid interfacial area. As a result, the spray reactor produces polymer-grade TPA in one step, eliminating the hydrogenation unit. Life cycle assessment confirms that the spray process without the hydrogenation unit significantly lowers global warming, acidification and other harmful emissions when compared to the MC process.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.