Chemical ManufacturingChemical Manufacturing

By: Robert McVicar & Brenna Lindsey-SweckerBy: Robert McVicar & Brenna Lindsey-Swecker

Main customers of chemical manufacturers are:• Auto industry• Agricultural industry• Housing industry, and • Product manufacturing industry

2The Chemical Industry is a principle contributor to the US economy

2Environment: Industry emits more than 1.5 million tons of categorized air pollutants

CHEMICAL MANUFACTURING: 1Raw materials from environment to industry and consumer useful products*Commodity = Large quantities, single chemical*Specialty = Small scale, “made to order”

Sulfuric Acid Sulfuric Acid 33The Most Important ChemicalThe 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 7x106 watts of electric power.

Uses of Sulfuric AcidAmazing number of applications…

Sulfuric Acid Production Process1. Obtaining sulfur: modern contact

process is used.

• Claus process utilized: H2S in natural gas is chemically separated then oxidized:

• 2H2S(g)+2O2(g) 1/2S8(g)+SO2+2H2O(g)

• 2H2S(g)+SO2(g) 3/8S8(g)+2H2O(g)

Sulfuric Acid Production ProcessSulfuric 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 ProcessSulfuric Acid Production Process2. From sulfur to sulfur dioxide.

• Sulfur is burned in air to obtain SO2

• 1/8S8(s) + O2(g) SO2(g)

• ΔH° = -297 kJ

Sulfuric Acid Production ProcessSulfuric Acid Production Process3. From sulfur dioxide to trioxide: the

contact process oxidizes SO2 with O2 to form SO3

• SO2(g) + 1/2O2 SO3(g)

ΔH° = -99 kJ

• Reaction is exothermic and occurs very slowly at room temperature.

Sulfuric Acid Production ProcessSulfuric Acid Production Process• Le Chatelier’s principle plays major role in third step.

Yield of SO3 Affected by…

Temperature

T Rate

TYield of SO3

Exothermic reaction therefore

shift to products

Catalyst used to maximize Rate & Yield

Pressure *small effect

ConcentrationDouble O2, Shift to Products. Remove SO3 as produced to encourage more production.

Sulfuric Acid Production ProcessSulfuric Acid Production Process

4. From sulfur trioxide to acid

• First a hydration step:

SO3(g) + H2O(l) H2SO4(l)

SO3(g) + H2SO4(l) H2S2O7(l)

H2S2O7(l) + H2O(l) 2H2SO4(l)

http://www.ism.ws/pubs/EmailNewsletters/ChemicalsNewsletter/eDigestChemicalDetail.cfm?ItemNumber=4640

ChlorineChlorineRanked in top ten chemicals produced in the United StatesRanked in top ten chemicals produced in the United States

4Used in over 50 percent of all industrial chemical processes: • 90 percent of pharmaceuticals• 96 percent of crop protection chemicals.

http://www4.uwm.edu/shwec/publications/newsletters/pills.jpg

ChlorineChlorineThe chlor-alkali process electrolyzes NaCl(aq) to produce Cl2 (and other important chemicals)

• Asbestos Diaphragm• Mercury-Cell • Membrane-Cell

http://www.bayertechnology.com/uploads/pics/chlorine_electrolysis_references_01.jpg

Electrolysis Plant

Chlor-alkali Process

Anode: Cl- oxidixedCathode: H20 reduced

Half-Reaction2Cl-(aq) Cl2(g) + 2e- Eo = 1.36v

2 H20 + 2e- 2OH-(aq) + H2(g) Eo = -1.0vTotal Ionic2Na+(aq) + 2Cl-(aq) + 2 H20 2Na+(aq) + 2OH-(aq) + H2(g) + Cl2(g)

Cathode compartment is a mix of NaCl and NaOH - NaCl removed by fractional crystallization

Electolysis of NaCl salt yields Cl2, H2 and NaOH

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Chlor-alkali ProcessAsbestos Diaphragm

Diaphragm separates half cell compartments

* Cl2 and H2 kept apart to prevent explosive combination

Chlor-alkali Process

Mercury-Cell

Mercury replaced at cathode(favors Na+ reduction) 2Cl-(aq) Cl2(g) + 2e-

2Na+(aq) + 2e- +Hg 2Na(Hg)

Sodium Amalgam treated with water2Na(Hg) + 2 H20 -Hg 2Na+(aq) + 2OH-(aq) + H2(g)

Being phased out due to water contamination - 200 g Hg per ton of Cl2 produced!

http://www.geneticmaize.com/2009/02/whats-in-the-corn-syrup-guest-post-by-renee-dufault/

Chlor-alkali Process

Membrane-CellReplaces Diaphragm with polymeric membrane - Allows cations to move through

Cl- removed at anode to form Cl2

Na+ ions travel through membrane

to cathode

Na+ ions form NaOH

*Uses less electricity and purity of NaOH

greater

Information ReferencesInformation References

1http://www.libraries.psu.edu/psul/business/industry_guides/chemical.htm

2http://www.epa.gov/ispd/chemical/index.html3Chemistry Textbook4http://worldchlorine.com/products/index.html