Phthalic Anhydride by Air Oxidation of Naphthalene: Gibbs and Conover, 1918

Harry D. Gibbs and Courtney Conover patented this in 1918, US 1,285,117 (filed 1917), and dedicated it to the public. Phthalic anhydride had been made by oxidising naphthalene with sulphuric acid in the presence of mercury sulphate; they used air instead. Naphthalene vapour mixed with plenty of air is passed over finely divided oxides of vanadium at 350–550 °C, and the phthalic anhydride formed is condensed and separated by fractional sublimation.

متقدم

Works process

التعليمات

Melt and vaporise the naphthalene

Melt the naphthalene and let it flow continuously, at a measured rate, into a heated chamber where it is volatilised.

المواد لهذه الخطوة:

نفثالين1 as required

الأدوات المطلوبة:

بوتقة صهر من حديد زهر

حجرة التبخير

ميزان حرارة

Mix the vapour with air

Mix the naphthalene vapour with air in excess of the amount needed to oxidise it to phthalic anhydride, preferably at least four times the amount theoretically required.

الأدوات المطلوبة:

نافخ هواء

حجرة التبخير

Pass it over vanadium oxide at 350–550 °C

Pass the mixture into a reaction chamber kept at 350–550 °C, preferably 500 °C. There it is forced into close contact with oxides of vanadium in the form of a fine powder, supported on trays, with baffle plates forcing the gas current through it. Keep the gases under pressure only sufficient to make them flow continuously through the chamber. The naphthalene is oxidised to phthalic anhydride, with carbon dioxide and water.

الأدوات المطلوبة:

حجرة حفّاز ذات صوانٍ

أكسيد الفاناديوم

مقياس الحرارة العالية

نافخ هواء

Condense the products

Condense the products of the reaction, phthalic anhydride with small portions of other oxidation products of naphthalene, together with the unchanged naphthalene.

الأدوات المطلوبة: