Ethanol From Acetic Acid

CHEN 4316: CHEMICAL PROCESS DESIGN II
DR. CARL D. MURPHY
PROJECT: ETHANOL FROM ACETIC ACID

JULIO VAZQUEZ

Ethanol from Acetic Acid
According to the Britannica Encyclopedia, acetic acid is considered the most important carboxylic acid. Carboxylic acids are compounds which contain a –COOH group attached. Carboxylic acids are acidic compounds because of the Hydrogen (H) in the COOH group.Acetic Acid is known as ethanoic acid or glacial acetic acid; its chemical formula is CH3COOH. Acetic acid is classified as a weak acid, but concentrated acetic acid is corrosive. Acetic acid is a colorless liquid miscible in water; it is the main compound to produce vinegar. In addition, acetic acid is useful to prepare metal acetates for printing processes, vinyl acetate for plastics,photographic films and textiles, among other chemical and biological processes. For industrial scale, acetic acid is manufactured by rhodium-iodine catalyzed carbonylation of methyl alcohol, a process developed by the chemical company Monsato in ths1960s.

In the other hand, according to the Britannica Encyclopedia, ethanol is an organic compound from the group of the alcohols –OH. Ethanol or ethylalcohol has a molecular formula of C2H5OH. Ethanol is an important industrial chemical since it is a valuable solvent, a fuel additive with gasoline, and the toxic ingredient for alcoholic beverages. Ethanol for human consumption is obtained from fermentation and it is applied in alcoholic beverages. In addition, ethanol can be manufacture as anhydrous or denature ethanol for industrial consumption.Finally, ethanol is obtained as a dilute aqueous solution and must be concentrated by fractional distillation.
Fermentation of carbohydrates and hydration of ethylene are the main processes to manufacture large scales of ethanol. However, hydration of ethylene is not an adequate long term process since ethylene is made of petroleum and natural gas, either fermentation of carbohydrates since rawmaterials are food for human consumption. Because fermentation of carbohydrates and hydration of ethylene are not viable long term processes, the production of ethanol from acetic acid can be an inexpensive alternate source to obtain ethanol.
The US patent number 4,421,939 was released on Dcember 20th, 1983 and was invented by Benn W. Kiff and David J. Schreck. In this patent the procedure explainsthe production of ethanol from acetic acid. The methodology to produce ethanol by this procedure is the following:
1. Produce a reaction between acetic acid and an olefinically unsaturated hydrocarbon of 4 to 10 carbon atoms. Some of the possible olefins for this experiment are the following: 1-butene, 2-butene, isobutene, 1-amylene, 2-amylene, 3-amylene, iso-amylene, 1-hexene, 2-hexene,3-hexene, 2-methyl1-2-pentene, 3-methyl1-2-pentene, 1-heptene, 1-octene, and cyclohexane among others. This reaction must happen in a tubular reactor with the presence of an acidic esterification catalyst to obtain an ester. The production of acetic acid is relatively cheap, while the olefin will react with acetic acid cleanly and readily to form an ester.
2. Ester must be hydrogenated;subsequently a mixture of ethanol and other alcohol is obtained. Hydrogenation of ester can be achieved in a conventional liquid phase reaction between a catalyst and liquid ester. This reaction must be heated to reach certain temperature and pressure. However, it is best to feed hydrogen and ester vapor to a tubular catalyst at the desire temperature and pressure. In this manner, a substantial amount ofester is converted while it is traveling through the catalyst and it is not necessary to filter out the product to recover the catalyst. Temperature and pressure of hydrogenation depend on the catalyst; however the range for temperature should not exceed 300°C, while the pressure should be less than 5000 psi.The mixture of alcohols from the ester hydrogenation contains the same number of carbons...