Lecture Topic 1:Introduction to the Chemical Industry

Premise: In order to discuss the place of chemistry in industry, we must consider the nature of the “Chemical Industry” and related industries in terms of economics and fundamental philosophies.

Goal: Students should be able to

1) describe the place of the “Chemical Industry” in the Canadian and world economy

2) describe the nature of the Canadian “Chemical Industry”

Chemistry and Industry

The “Chemical Industry”

• a term referring to a statistical entity tracked by economic analysts

• includes the production of chemicals (pharmaceuticals, pesticides, etc.) and chemical products (plastics, paints, dyes etc.)

• traditionally, does not include production of steel, glass, paper etc.

Other relevant industries

• steel• aluminum• glass• ceramics• pulp and paper• petroleum• natural gas• etc.

Characteristics of the Chemical Industry

1) Basic objective - make a profit

2) Very competitive - there are hundreds of chemical companies, both small and very large…there tend not to

be monopolies

3) Highly dependent on science and technology

4) Spends large amounts of its money on R&D

5) Large capital requirements - to construct, expand and maintain production facilities

6) Low labor requirements - BUT needs highly qualified personnel

7) Industry Growth - generally through integration rather than diversification

The Chemical Sector at a Glance

Chemicals and chemical products:

• account for ~10% of total world trade in all commodities

• are the 2nd largest single item of global trade (road vehicles being the 1st).

World Chemicals Output (2002): $1.6 Trillion USD !• Europe 31%• USA 28%• Asia/Pacific 27%• Other* 14%

*Other: Latin America, non-E.U. Europe, Africa, Oceania, Canada

The Chemical Sector at a Glance

World’s largest chemical producer : U.S.A.

(World’s largest chemical exporter : Germany)

North American Chemicals Output (2002): $505 Billion USD

• USA 92% ($467 Billion USD)• Canada 5% ($23 Billion USD)• Mexico 3% ($15 Billion USD)

Canada’s Chemical Leaders

1. Nova Chemicals (public) 2. Potash Corp. Sask. (public) 3. Dow Chemical Canada (100% Dow) 4. Agrium (public) 5. DuPont (77% DuPont) 6. Methanex (37% Nova) 7. Imperial Oil (70% Exxon-Mobil) 8. ICI Canada (100% ICI) 9. BASF (100% BASF)10. Shell Canada (78% Royal Dutch Shell)11. Celanese Canada (100% Celanese AG)12. Petromont (50% Dow Chemical, 50% Prov. Quebec)13. Rhône-Poulenc Canada (100% Rhône-Poulenc)14. CXY Chemicals (100% Nexen)15. AT Plastics (public)

Premise: There are fundamental differences between the design of a chemical synthesis for industry and that for a research laboratory.

Goal: Students should be able to

1) explain how industrial synthetic approaches differ from laboratory synthesis methods.

2) evaluate possible reaction schemes based on thermodynamic, economic, and other considerations.

Laboratory Chemistry vs. Industrial Chemistry

Differences in the Synthetic Approach

e.g., formation of ethyl alcohol by hydration of ethylene:

H2C CH2 + H2OH

H3C

H2C

OH

Laboratory Scale• bubble ethylene into 98% H2SO4

• dilute and warm the reaction mixture to hydrolyze the resultant sulfate ester

Industrial Scale• a stream of ethylene is mixed with steam at 325°C and 1000 psi and passed over a solid catalyst consisting of phosphoric acid absorbed on diatomaceous earth; the process is run continuously, and unreacted ethylene is recovered and recycled to the feed stream.

Different Approaches for Different Objectives

Laboratory Objectives• synthesize the product in the most convenient manner considering:

1) chemist’s time2) equipment available (usually must use glassware)3) conditions achievable (usually close to ambient pressure and between -195.8° C (N2(l)) and 132° C (chlorobenzene).

Industrial Objectives• produce the product at minimum total cost on a scale that will generate the maximum economic return.• may use:

1) large range of temperatures and pressures2) batch process or continuous operation3) reactants in vapor phase or liquid phase

Evaluation of a Reaction

If a chemist has an idea for an industrial scale process, what are the steps that must be taken before the process can be implemented?

1) Evaluation of the reaction: Before any serious literature search or laboratory work is started, various possible strategies are proposed.

2) Economic feasibility

3) Technical feasibility

4) Other considerations: environmental issues, etc.

Evaluation of a ReactionThe chemist must consider not only the well-known, obvious approaches, but also unknown or untested approaches.

e.g., the manufacture of ethylamine

1.

2.

3.

4.

5.

6.

7.

8.

CH3CH2Cl + 2 NH3 CH3CH2NH2 + 2 NH4Cl

C NH3C + 2 H2 CH3CH2NH2

CH3CH2NO2 + 3 H2 CH3CH2NH2 + 2 H2O

H3C H

O

+ NH2OH + 2 H2CH3CH2NH2 + 2 H2O

H3C H

O

+ NH3 CH3CH2NH2 + 2 H2O

CH3CH2OH + NH3 CH3CH2NH2 + H2O

H2C CH2 + NH3 CH3CH2NH2

H3C CH3 + 0.5 N2 + 0.5 H2 CH3CH2NH2

Economic Feasibility

Estimate the difference between the market value of the products and the reactants.

First approximation, assume:

1) 100% yield2) no costs of solvents or catalysts3) no value for co-products

These assumptions must be reassessed further on in the development stage.

Technical Feasibility

There are two basic questions that a chemist or chemical engineer must ask concerning a given chemical reaction:

(1) How far does it go, if it is allowed to proceed to equilibrium? (Does it go in the direction of interest at all?)

(2) How fast does it progress?

Question (1) is concerned with thermodynamics and amounts to evaluating the equilibrium constant (K).

Question (2) is a matter of kinetics and reduces to the need to know the rate equation and rate constants (k).

Technical Feasibility

Generally, the first approach is to consider the thermodynamics of the reaction.

This may be done by evaluating the change in Gibbs free energy (ΔG).

ΔGR = ΔHR - T ΔSR

A spontaneous reaction has a decrease in Gibbs energy of the system.

To calculate the Gibbs energy of reaction, use standard Gibbs energies of formation ΔGf°.

ΔGreaction = ΣΔGf°products - ΣΔGf°reactants

Example: Dissociation of ethyl chloride

CH3CH2Cl H2C CH2 + HCl

At 298 K

ΔHf° -26.70 12.50 -22.06ΔGf° -14.34 16.28 -22.77S°

At 1000 KΔHf° -30.43 9.21 -22.56ΔGf° 18.60 28.85 -24.08S° 93.80 72.07 53.25

CH3CH2Cl H2C CH2 HCl

ΔHrxn = ΔHf°CH2=CH2 + ΔHf°HCl - ΔHf°CH3CH2Cl ΔGrxn = ΔGf°CH2=CH2 + ΔGf°HCl - ΔGf°CH3CH2Cl

ΔSrxn = S°CH2=CH2 + S°HCl - S°CH3CH2Cl

At 298 K: ΔHrxn = +17.14 kcal/mole ΔGrxn = +7.86 kcal/mole ΔSrxn = +31.15 cal/mole

At 1000 K: ΔHrxn = +17.08 kcal/mole ΔGrxn = -14.43 kcal/mole ΔSrxn = +31.52 cal/mole

- ΔG at 1000 K only!

Change in Free Energy Indication-ΔG promising

small +ΔG worth further investigationlarge +ΔG possible only under unusual conditions

ΔGf° kcal/mol298 K 1000 K

CH2=CH2 16.28 28.25CH3-CH3 -7.87 26.13CH3CH2NH2 8.91 60.96CH3CH2OH -40.22 1.98NH3 -3.86 14.85H2O -54.64 -46.04H2 0 0N2 0 0

ΔGreaction = ΣΔGf°products - ΣΔGf°reactants

ΔG298 = -1.65 kcal/molΔG1000= -1.91 kcal/mol

H3C CH3 + 0.5 N2 + 0.5 H2 CH3CH2NH2

CH3CH2OH + NH3 CH3CH2NH2 + H2O

ΔG298 = + 16.78 kcal/molΔG1000= + 34.83 kcal/mol

Question: Under what conditions would the following reaction be the most promising?

H2C CH2 + NH3 CH3CH2NH2

ΔG298 = - 3.51 kcal/molΔG1000= + 17.86 kcal/mol

Temperature?

Pressure?

Stoichiometry?

Other Considerations

Evaluate:

• number of possible side-products (and separation difficulties)

• air or moisture sensitivity of reactants and intermediates

• commercial value of side-products

• environmental impact of side-products

• health and safety issues