Chemical Manufacturing By: Robert McVicar & Brenna Lindsey-Swecker

Main customers of chemical manufacturers are: Auto industry Agricultural industry Housing industry, and Product manufacturing industry 2 The Chemical Industry is a principle contributor to the US economy 2 Environment: Industry emits more than 1.5 million tons of categorized air pollutants CHEMICAL MANUFACTURING: 1 Raw materials from environment to industry and consumer useful products *Commodity = Large quantities, single chemical *Specialty = Small scale, “made to order”

Sulfuric Acid 3 The Most Important Chemical Has been manufactured for more than 400 years 150 million tons of sulfuric acid is produced annually A nation’s level of sulfur production can be used to indicate the nation’s industrial compactly. Surprisingly inexpensive ($150/ton) –Each step is an exothermic process –Heat is sold as energy Average daily production of sulfuric acid produces 7x10 6 watts of electric power.

Uses of Sulfuric Acid Amazing number of applications…

Sulfuric Acid Production Process 1. Obtaining sulfur: modern contact process is used. Claus process utilized: H 2 S in natural gas is chemically separated then oxidized: 2H 2 S (g) +2O 2(g)  1 / 2 S 8(g) +SO 2 +2H 2 O (g) 2H 2 S (g) +SO 2(g)  3 / 8 S 8(g) +2H 2 O (g)

Sulfuric Acid Production Process When natural gas is not readily available but there are natural underground deposits the Frasch process is utilized: A hole is drilled, superheated water melts the sulfur. A combination of hydrostatic pressure and the pressure of condensed air force the sulfur to the surface. Produces a very pure substance.

Sulfuric Acid Production Process 2. From sulfur to sulfur dioxide. Sulfur is burned in air to obtain SO 2 1 / 8 S 8(s) + O 2(g)  SO 2(g) ΔH° = -297 kJ

Sulfuric Acid Production Process 3. From sulfur dioxide to trioxide: the contact process oxidizes SO 2 with O 2 to form SO 3 SO 2(g) + 1 / 2 O 2  SO 3(g) ΔH° = -99 kJ Reaction is exothermic and occurs very slowly at room temperature.

Sulfuric Acid Production Process Le Chatelier’s principle plays major role in third step. Yield of SO 3 Affected by… Temperature TT  Rate TT  Yield of SO 3 Exothermic reaction therefore shift to products Catalyst used to maximize Rate & Yield Pressure*small effect Concentration Double O 2, Shift to Products. Remove SO 3 as produced to encourage more production.

Sulfuric Acid Production Process 4. From sulfur trioxide to acid First a hydration step: SO 3(g) + H 2 O (l)  H 2 SO 4(l) SO 3(g) + H 2 SO 4(l)  H 2 S 2 O 7(l) H 2 S 2 O 7(l) + H 2 O (l)  2H 2 SO 4(l)

ws/pubs/ Newsletters/ChemicalsNewsletter/eDigestChemicalDetail.cfm?ItemNumber=4640 Chlorine Ranked in top ten chemicals produced in the United States 4 Used in over 50 percent of all industrial chemical processes: 90 percent of pharmaceuticals 96 percent of crop protection chemicals.

Chlorine The chlor-alkali process electrolyzes NaCl(aq) to produce Cl 2 (and other important chemicals) Asbestos Diaphragm Mercury-Cell Membrane-Cell Electrolysis Plant

Chlor-alkali Process Anode: Cl - oxidixed Cathode: H 2 0 reduced Half-Reaction 2Cl - (aq)  Cl 2 (g) + 2e - E o = 1.36v 2 H e -  2OH - (aq) + H 2 (g) E o = -1.0v Total Ionic 2Na + (aq) + 2Cl - (aq) + 2 H 2 0  2Na + (aq) + 2OH - (aq) + H 2 (g) + Cl 2 (g) Cathode compartment is a mix of NaCl and NaOH - NaCl removed by fractional crystallization Electolysis of NaCl salt yields Cl 2, H 2 and NaOH

Chlor-alkali Process Asbestos Diaphragm Diaphragm separates half cell compartments * Cl 2 and H 2 kept apart to prevent explosive combination

Chlor-alkali Process Mercury-Cell Mercury replaced at cathode(favors Na + reduction) 2Cl - (aq)  Cl 2 (g) + 2e - 2Na + (aq) + 2e - +Hg  2Na(Hg) Sodium Amalgam treated with water 2Na(Hg) + 2 H 2 0 -Hg  2Na + (aq) + 2OH - (aq) + H 2 (g) Being phased out due to water contamination g Hg per ton of Cl 2 produced!

Chlor-alkali Process Membrane-Cell Replaces Diaphragm with polymeric membrane - Allows cations to move through Cl - removed at anode to form Cl 2 Na + ions travel through membrane to cathode Na + ions form NaOH *Uses less electricity and purity of NaOH greater

Information References 1 chemical.htm Chemistry Textbook 4