Acetic Acid By Hamad Shaabi Reyan Rutherford Shaun Lynn Andrew Pollock Marketing Acetic Acid Demand Major Region South America 2% Acetic Acid Supply Major Region Rest of the Middle East World Europe 3% 2% 11% North America 22% Middle East 23% Europe 14% Asia 57% Asia 60% South America 2% North America 4% Region Demand Supply Import Export Asia 37 57 - 20 North America 22 4 18 - South America 2 2 - - Europe 11 14 - 3 Middles East 2 23 - 20 Marketing Global Acetic Acid Derivatives Others 27% Acetic Anhydride 8% Acetate Esters 11% Vinyl Acetate Monomer 37% Terephthalic Acid 17% Acetic acid Derivatives Uses Vinyl Acetate Monomer Paints, adhesives, coating, textiles, wire and cable polyethylene compounds Terephthalic Acid Bottles, textiles, polyester fibers Acetate Esters Paints, coating, inks formulation, sealants, adhesives in pharmaceutical applications Acetic Anhydride Cellulose acetate fibers, plastics, pharmaceutical such as aspirin Others Chemical reagent Method Ethylene via acetaldehyde Methanol by carbonylation Butane by liquid-phase oxidation Cativa Process Ethylene via acetaldehyde OFF Gas CO2 Removal Steam stm stm [PdCl4]²ˉ C2H4 + H2O + ½O2 CH3CHO + H2O CuCl2 CH3CHO + H2O CH3COOH + H2 Extraction System water Acetic Acid Product Acetic acid Extractor Nitrogen Acetaldehyde Column Ethylen e Oxygen Acetaldehyde Acetic Acid Column Reactor 106 °C 10 ATM Acetic Acid scrubber BFW Flash tank H2O Estimating plant capital costs Major Process Step Special Requirements Score Reaction 10 atm (0.3), Temp 160 °C(0.3) ,H.G Stainless steel (0.6) 2.2 Scrubber High grade s.s. (0.6) 1.6 CO2 Removal High grade s.s. (0.6) 1.6 Acetic Column High grade s.s. (0.6) 1.6 Acetaldehyde Column High grade s.s. (0.6) 1.6 Acetic Finishing High grade s.s. (0.6) , entrainment (0.3) 1.9 Total process complexity factor 10.5 Methanol Carbonylation Methanol Carbonylation Most used process for production of Acetic acid. Developed by Henry Dreyfus at British Celanese, pilot plant opened in 1925. Uses a metal catalyst, usually Rhodium. CH3OH + CO CH3COOH Methanol Carbonylation 1. CH3OH + HI CH3I + H2O 2. CH3I + CO + [Metal Catalyst] CH3COI 3. CH3COI + H2O CH3COOH + HI H2O CH3OH HI HI CH3I Reaction carried out at a minimum of 200atm. CH3COI H2O CH3COOH Methanol Carbonylation • Methanol and carbon monoxide are the raw materials. • Bi-products are separated using distillation. Methanol Carbonylation Flow Diagram Methanol Carbonylation Complexity Factor Major Process Step Special Requirements Score Reaction 200 atm (0.9) Temp 200 °C(0.3) High Grade Stainless steel (0.6) 2.8 Scrubber High Grade Stainless steel (0.6) 1.6 CO2 Removal High Grade Stainless steel (0.6) 1.6 Acetic Column High Grade Stainless steel (0.6) 1.6 Acetaldehyde Column High Grade Stainless steel (0.6) 1.6 Acetic Finishing Entrainment (0.3) High Grade Stainless steel (0.6) 1.9 Total process complexity factor 11.1 Cativa Process Cativa • Developed in 1996 by BP. • Uses Iridium catalyst. • Requires Catalytic Promoter – Ruthenium • Increase in“active anionic” species Ir(CO2)I3Me]- Mechanism of Iridium Catalysed Reaction Cativa Process • First step is no longer the rate determining step • Cativa Process 150x faster than Monosanto • Rate = [catalyst] x [CO] [I-] • Very high yield 95-98% at 99% purity Cativa Flow diagram Advantages of the Cativa process • Iridium is much cheaper than rhodium • Less iridium is needed because it is so stable that all the catalyst is recycled in the plant • The reaction is faster and the quantities of by-products are much lower, reducing the purification costs. For example steam is used to heat the distillation columns and there is a 30% saving of steam over the Monsanto process • Some conversion of CO to CO2 still occurs but at a much lower rate • CO utilisation is increased from about 85% to over 94% • Overall the Cativa process releases about 30% less CO2 per tonne of product than does the rhodium process Butane by liquid-phase oxidation Acetic Acid by Butane Oxidation • When butane is heated with air in the presence of a metal catalysts acetic acid is produced. C4H10 + 2½ O2 → 2 CH3COOH + H2O • Suitanle metal catalysts are manganese, cobalt and chromium. • Conditions are run at a combination of temperature and pressure designed to be as hot as possible while keeping the butane in a liquid phase. Typical conditions are 150°C an 55 atm. • The reaction produces side products such as ethyl acetate, butanone and formic acid which are commercially valuable. • Reaction conditions can be altered to produce either of these as the major product if this is economically useful. • Before methanol carbonylation became commercialised in the 1980s, Butane oxidation was the major source of acetic acid • Now produces less than 10% of acetic acid supply annually. Thank you any question ? References: G. James, chemical process and design hand book, USA 2001 A. John & Encyclopedia of chemical technology ullmann’s & encyclopedia of industrial chemistry