Method for preparing phthalic acid by xylol co-oxidation catalyst system

• Main Authors: GUO LINGTONG, SUN XUJIANG, ZHAO KEPIN, LI JUN, ZHENG WEIHUA, CUI FENGXIA
• Format: Patent
• Language: Chinese; English
• Published: 13.02.2013
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; METALLURGY; ORGANIC CHEMISTRY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; THEIR RELEVANT APPARATUS; TRANSPORTING

The invention relates to a method for preparing phthalic acid by a xylol co-oxidation catalyst system. The method comprises that air or oxygen-rich air as an oxidant undergoes a liquid-phase oxidation reaction at a temperature of 160 to 210 DEG C under the pressure of 0.5 to 2.0MPa in the presence of the traditional Co-Mn-Br catalyst added with a transition metal cocatalyst and/or an imide cocatalyst, and acetic acid as a solvent to produce mixed phthalic acid-containing slurry; and the mixed phthalic acid-containing slurry is subjected to separation refining. Through the transition metal cocatalyst, a reaction rate is improved. Through the imide cocatalyst, a use amount of strongly corrosive bromide ions is reduced. M-phthalic acid and p-phthalic acid can be directly used for copolyester production without separation so that a xylene separation cost is reduced. The method can be used basically without a change of the existing p-xylene oxidation device. The method has a fast oxidation reaction rate, is conduc