Company // Sustainability

Sustainable business

Sustainability is a major priority in CABB's day-to-day operations. In this connection, our aim is not merely to save energy, reduce greenhouse gas emissions and maximise our use of renewable resources. For us, sustainability also relates to how we treat employees, prevent accidents and provide our staff with opportunities for continuing training and ongoing personal growth.

Creating value

As a manufacturing enterprise, our focus is on the energy-friendly and environmentally friendly use of resources. Our Verbund system plays a major role in this effort by helping us to conserve energy and resources, reduce emissions and waste flows and cut logistics costs. This system transforms by-products into valuable raw materials for other products. Heat produced at one point in our production processes can be reused elsewhere.

Green Chemistry

Sustainability in the chemical industry is more than biobased chemicals and renewable feedstocks, as it unites economic success, environmental protection and social responsibility. To qualify what is "green chemistry", the American Chemical Society (ACS) has edited the "12 Principles of Green Chemistry". 

These include above all the prevention of waste, the reduction of solvents, atom and energy efficient processes, and safe production processes. CABB is heavily involved in these topics, as the case studies below show. In addition, continuous product and process optimisation is part of CABB's Integrated Management System and therefore part of CABB's business processes. 

To determine the material and waste efficiency of chemical manufacturing processes, the Process Mass Intensity (PMI) and the Environmental factor (E-factor) are used. The PMI puts into ratio the total amount of raw materials including solvents and water with the amount of product. The E-factor puts into ratio the total amount of waste which is formed with the amount of product. 

Continuous processes are considered a key feature for green manufacturing. In general, economics of a continuous process are expected to be superior to a batch process. One additional important aspect is safety, as volumes are smaller, heat transfer is faster and the reaction runs in a steady state instead of an alternating change of conditions. CABB has a longstanding experience in the design and handling of continuous processes.

www.acs.org 

Case study: Chlorination
Chlorierung

Chlorinations are carried out in the fine chemicals industry mainly by using thionyl chloride. During the course of the chlorination reaction, hydrochloric gas and sulfur dioxide are generated as off-gases. In general, these off-gases are disposed by absorption in a caustic scrubber. Large volumes of base are needed and large amounts of waste water containing salts are generated (see scheme at the left).

Chlorination reactions at CABB benefit strongly from the Verbund and recycling system where thionyl chloride is produced on-site and is fed directly from storage tanks via pipeline into the reactors. The off-gases HCl and SO2 are separated and purified. Hydrochloric gas is absorbed in water to form commercial hydrochloric acid. The sulphur dioxide is re-oxidised into sulphur trioxide, which is the raw material for our thionyl chloride production (scheme at the right).

 

Conventional scrubber system

CABB's Verbund system

PMI 6.3 2.1
E-Faktor 4.7 0.04

* PMI = process mass index (according to ACS Green Chemistry Institute)
** E-Faktor = environmental factor (according to Roger Sheldon)

Results:
In the conventional chlorination process large amounts of caustic soda are required for the absorption of the off-gases. The formed salts are disposed as aqueous waste. This is reflected in the PMI and the E-factor. The CABB Verbund and recycling system shows significant benefits for chlorination processes: no caustic soda is needed and therefore the material input is lower, which leads to a PMI factor which is 67 % lower than for the conventional process. The large amounts of waste water in the conventional process are the reason for the higher number of the E-factor compared to the E-factor value of the Verbund system. There, all off-gases are recycled or converted into commmercial products and only very small volumes of waste are generated.

Benefits of the Verbund system:
- no caustic soda required
- no waste water generated
- sulphur dioxide is completely recycled
- hydrochloric gas is transferred into a commercial product
- highly efficient use of energy and materials

 
Case study: Sulphonation/Chlorosulphonation
Chlorierung
Conventional process
Sulphonation and chlorosulphonation are often used in pharma and agro syntheses to generate sulfonamides and further downstream products. Both processes create a lot of waste and are inefficient regarding the use of materials. The standard reagent is chlorosulphonic acid: in the first step the sulphonic acid group is transfered and hydrochloric gas is formed as off-gas. In the second step only the chlorine of the chlorosulphonic acid is used for the formation of the sulphonyl chloride and diluted sulphuric acid results as waste. The advantage of this process is the use of one single reagent for two different reactions, but one of two moles of chlorosulphonic acid is disposed in form of diluted acids at the end. Both steps are generally carried out in an organic solvent.
 
CABB process
CABB carries out chlorosulphonation processes with sulphur trioxide as sulphonation reagent in liquid sulphur dioxide as solvent. After the reaction is completed, SO2 is evaporated back into the recycling system by elevating the temperature and is thus at 100 % recycled. This sulphonation reaction does not create any side products or waste. The chlorination reaction in the second step is carried out with thionyl chloride with no additional solvent. The off-gases HCl and SO2 are separated and purified. Hydrochloric gas is absorbed in water to form commercial hydrochloric acid. The sulphur dioxide is re-oxidised into sulphur trioxide, which is the raw material for our thionyl chloride production. The subsequent amide formation is identical in both processes.
 
 

Conventional process

CABB process

PMI 20.2 10.4
E-Faktor 19.0 6.7

* PMI = process mass index (according to ACS Green Chemistry Institute)
** E-Faktor = environmental factor (according to Roger Sheldon

Results:
The CABB chlorosulphonation process consumes much less materials and creates less waste compared to the conventional process. The PMI shows that the input of materials is significantly lower in the CABB process as no caustic soda for scrubbing of off-gases is required, resulting in a 50 % reduced PMI for the CABB process. The conventional process requires two moles of chlorosulphonic acid from which one mole is disposed as diluted acids at the end. The E-factor reflects this situation with a value which is three times higher than for the CABB process. Here, no waste is generated from the chlorosulphonation process. 

Benefits of the Verbund system:
- highly efficient use of materials and energy
- significant lower waste generation
- no waste water generation
- no additional organic solvent
- sulphur dioxide as solvent is completely recyled

 
Case study: Continuous reactions
Chlorierung

Continuous processes are considered as a key feature for green manufacturing. Apart from better economics, safety is one additional important aspect, as reaction volumes in continuous processes are smaller and heat transfer is faster than in batch processes and the reaction runs in a steady state.

The Wolff-Kishner reaction is an example for a process which needs to be carried out in a continuous reaction on a commercial scale because of process safety. The reason is the large volume of gas which is released during the reaction. In a batch process, the whole gas volume is released at once exceeding a certain reaction temperature. In the continuous process only small volumes of gas evolve continuously, which can be safely controlled.

 

Batch process

CABB continuous process

PMI - 2.51
E-Faktor - 1.38

* PMI = process mass index (according to ACS Green Chemistry Institute)
** E-Faktor = environmental factor (according to Roger Sheldon)

Result:
The values for the batch process cannot be determined as it cannot be realised at this commercial scale. However, the low PMI and E-factor values of the CABB process show, that the continuous CABB process is highly efficient regarding use of materials and formation of waste. CABB has a longstanding experience in the design of continuous processes. 

Benefits of the CABB continuous process:
- efficient use of energy and materials
- safe handling of challenging processes
- longstanding experience in design and handling of continuous processes