Patent CA-2145317-A1 (CA)
Title: Method for purification of phenol
Inventor: ZAKOSHANSKY VLADIMIR M
IPC: C07C39/04
Filed: 1995-03-23
Abstract: The invention relates to a method for purification of phenol and specifically to a method for purification of phenol produced within the process of joint phenol and acetone production by cumene method.      The aim of the invention is to develop a catalyst which has high activity for phenol purification from organic mico-impurities with regeneration of the catalyst and which has high mechanical strength and stability with long catalyst life.      This result is obtained by phenol purification using a heterogeneous zeolite catalyst. The acidity of the catalyst measured by butane cracking (KA) is more than 10.      It is preferable to use zeolites which are designated according to the classification of the International Zeolite Association by indices FAU (zeolites X, Y), MFI (for example, ZSM-5), MOR (mordenite), MAZ (omega), BEA (beta), FER (ferrierite) and others. These zeolites can be used with binders (aluminum oxide, silica gel, aluminosilicates or aluminophosphates) and without them. It is preferable to use zeolite of the Y type with an aluminosilicate binder and a the value of KA = 50-80 cm3/min*g and Si/Al ratio more than 3. The concentration of sodium, potassium and other alkali agents on the basis of their oxides does not exceed 2 wt%, preferably not more than 0.3 wt%. It is preferable to use zeolites with medium and large pores. Size of zeolites pores should be within the range 4A° in diameter and more. The most preferable zeolites are with large pores (>6A° in diameter) such as Y and mordenite.      Phenol derived from distillation of heavies and lights and still containing impurities i.e., hydroxyacetone, mesityl oxide, &-methylstyrene, 2-methylbenzofurane and other carbonyl compounds and not containing water (water content not more than 1 wt%, preferably less than 0.1 wt% ) contacts the zeolite catalyst at a temperature between about 120 to 250°C (preferably 180 to 200°C) and space velocities 0.1- 3.5 hr-1 (preferably 0.8 - 1.2 hr-1).      It has been discovered that said purification results in conversion of such impurities as mesityl oxide, hydroxyacetone, &-methylstyrene and other carbonyl compounds of not less than 90%. It is important that the above mentioned impurities are converted into the products of condensation under the catalyst effect and purification conditions, and so that these impurities can be separated from phenol by further rectification and removed from the process along with other "heavy" products, so-called "phenol tar". At high space velocities (more than 0.8 hr-1) there is an increase in the amount of 2-methylbenzofurane which can be easily removed from phenol by distillation. At low space velocities (less than 0.8 hr-1) and high temperatures (more than 200°C) there is a decrease in 2-methylbenzofurane amount (conversion is not more than 50% ). Acidity of zeolites active centers can be stabilized by rare-earth elements (e.g. lanthanum and others). The stable catalyst can be used for a long time and at high micro-impurities content in the purified phenol. The life of the above mentioned catalysts is not less than three years.       After rectification the phenol product meets the requirements for production of caprolactam and Bisphenol A.