2.3 Optimizing Production Chemical Industry

What is Chemical Industry? The large scale production of commercially beneficial chemical products through a series of chemical reactions and physical processes Discussion Question What are some industrial processes you can think of? Describe them in a few sentences

What are some characteristics of general industry? Industry involves a series of steps in the production of goods. For example, production of cars isn’t as simple as Steel in – Car out Leather Rubber Electronics

So is this the same for chemical industry? Haber Process for Ammonia Production N2(g) + 3H2(g) ⇄ 2NH3(g) Do you think the production of Ammonia occurs in a single physical process?

Reaction Vessel Cooler Ammonia Production actually occurs in a series of stages, with a variety of chemical conditions taking place at each stage.

Chemical Industry utilizes a step-wise approach for product formation Chemical Plants act as networks of structures that reflect the nature of the processes

How do we represent the step-wise nature of chemical industry? Especially considering the amount of chemical reactions and physical processes that take place

Flow-Charts Visual Representation of the flow of materials through the various components of a plant. Some of these components can include…. - Cooler - Purifier Reformer (reaction center) Converter

Raw Materials Raw Materials are substances which are converted to useful products through physical or chemicals reactions They can include: Coal or oil Air Water Salt Metal Ores Discussion Question: “How do you think raw materials are represented on flow charts?” Water Air Reactor Chemical i.e. Nitrogen

Waste Products Often chemical conversion processes produce products that have no further use within the market, and as such require disposal. These chemicals are known as Waste Products and present as economic and environmental problems to companies. Unreacted Gases Absorber Impurities

By-Products Sometimes, products are given off that are not the ‘main product’ of interest but rather another substance products which still holds further or commercial value. These are known as by-products. Common examples of By-Products are Carbon Dioxide, which is an important component of many chemical reactions, and Water, which may be diverted for cooling. Carbon Dioxide Condenser Converter Water

Real-life Example: Methanol Production

What Goes in. What Comes Out What Goes in? What Comes Out? What are some interesting points about the equations?

Past Exam Question Identify two raw materials added to the absorber for nitric acid production Identify a waste product produced in the process Describe one way the efficiency of the system above has been improved

Chemical Industry and the environment Environmental Considerations: Waste Disposal - Energy Usage Resource Use Storage? Effect on waterways? Greenhouse Gas Emissions? What produces the energy? Sustainability? Transport of resources? Effective use of Reactants?

Green Chemistry Principle Guidelines for developing chemical processes around reducing the production of hazardous or environmentally damaging chemicals. We will examine 3 in particular Energy Efficiency Atom Economy Catalysis https://www.epa.gov/greenchemistry/basics-green-chemistry

Designing for Energy Efficiency

Atom Economy Catalysis “Synthetic methods are designed to maximize incorporation of all materials used in the process into the final product” Having the greatest conversion of reactants to products possible i.e. getting as close to the theoretical yield as possible. Having a high conversion rate also has many ECONOMIC benefits to companies Catalysis “Catalytic reagents are superior to stoichiometric reagents in chemical industry” Revision: What are catalysts? What are they beneficial to chemical reactions? In principle, they can be used in small amounts and recycled indefinitely, increasing efficiency of conversion

Maximizing Yield What is Yield? Actual Yield Theoretical Yield The quantity of product that is obtained in the process. This takes into account reaction conditions and economic considerations Quantity of product predicted by the stoichiometry of the reaction. This is the ideal amount of product that can be formed

Maximizing Yield CaCO3(s) ⇄ CaO(s) + CO2(g) ΔH = +178 kJmol-1 Within industries, there is a tender interplay between maximising the yield and maintaining economically favourable conditions Lets look at the chemical process for generating quicklime from limestone CaCO3(s) ⇄ CaO(s) + CO2(g) ΔH = +178 kJmol-1 Discuss with the person next to you the important points you take from this equation

Maximizing Yield CaCO3(s) ⇄ CaO(s) + CO2(g) ΔH = +178 kJmol-1 Equilibrium Reaction Highly endothermic 3. Production of Carbon Dioxide

Industrial Compromise Industries utilise a form of compromise when undertaking chemical synthesis. While for some reactions it may be favourable to have high temperature or pressure, the economic costs for maintaining them may outweigh the benefits. Therefore, some yield may have to be sacrificed in order to give a more economic rate of product formation. High$ Very-High Temperatures Maximum Yield Endothermic Reaction High Temperatures High Yield Moderate$ Same Principle applies with Pressure and Catalyst use

Industrial Compromise Environmental Consequences High Temperatures High Pressure Increased Energy Requirements Increased costs Sacrificing some yield for economic and environmental reasons is common place for most chemical industry processes Knowing this, why do you think using a catalyst is beneficial for industrial processes?

Note that the generic example shown is for an Endothermic Reaction Will the same still apply in an Exothermic Reaction? Hint: Le Chatelier’s Principle

Note the different percentages at different temperatures Percentage of Product at equilibrium What considerations should we make at the different temperature and pressures? Pressure

Nitric Acid Production The production of Nitric Acid from Ammonia and Nitrogen Monoxide consists of two exothermic steps, which occur in the reactor and absorber (see page 209) Moderately high temperatures are used, why is this the case? The absorber reaction is shown below, what pressure consideration would you make?

Case Study: Sulfuric Acid In groups of 3, you will be researching into and making a concise poster about the chemical production of Sulfuric Acid Some things to Consider and present on your poster: What are the reactions that are taking place? Why is Sulfuric Acid production so important? What are the conditions that are utilised? WHY are these conditions utilised? What environmentally friendly measures have been taken? Due Date: Friday It is important that you integrate your knowledge from Rates of Reaction and Equilibrium when explaining the points above