Our latest blog series is designed to guide chemists towards a greener, more sustainable laboratory. Each of our blogs will explore one principle. If you missed previous ones, they can be found here.
Ninth Principle: Catalysis – Use Catalysts, Not Stoichiometric Reagents
A Paradigm Shift
As highlighted on the ACS Green Chemistry site, Roger A. Sheldon, Ph.D., Emeritus Professor of Biocatalysis and Organic Chemistry at Delft University of Technology and CEO of CLEA Technologies B.V., distills much of green chemistry down to two core ideas: prevention and effectiveness. In his words, “prevent rather than cure”—or more plainly, it is easier to avoid a spill than to clean it up.¹ ² This perspective reinforces the first two principles of green chemistry.
Sheldon explains that achieving true efficiency in organic synthesis requires “a paradigm shift… from one that is focused on chemical yield to one that assigns value to minimization of waste” (Principle 1). Catalysis is central to maximizing atom economy (Principle 2), and ties directly to the E-factor (environmental factor) concept he developed.³ The E-factor measures waste generated per unit of product— The lower the E factor, the less waste are generated and thus the greener the process. [FG1]
Indispensable for Industrial Production
Decades before green chemistry principles were formally established, catalysis was already a cornerstone of industrial processes such as oil refining and polymer production. As noted in a 2008 article, “Catalysis presents a key technology to enable energy and resource efficient chemical transformations” and remains “indispensable” for large-scale fuel and bulk chemical manufacturing.⁴ Catalysts are not inherently more compatible with green solvents.
However, when a catalyst is both selective and used with a green solvent, the combined effect can significantly reduce the E-factor beyond what the solvent alone would achieve.
Other Factors to Consider
To fully appreciate the role of catalysis, it’s important to understand the two main types of catalysts: [FG3] heterogeneous and homogeneous. Homogeneous catalysts often yield higher amounts of the desired product but can present challenges in fine chemical and pharmaceutical production due to metal contamination considerations.⁵ Importantly, catalysts are not inherently more selective than stoichiometric reagents—selectivity depends on the specific reaction. Yet when performance and cost are comparable, catalysts are generally preferred because they reduce the amount of reagents required, contributing to greater efficiency and sustainability.
This principle is especially relevant in cell and gene therapy (CGT) manufacturing, where enzyme-driven biological reactions play a central role. Catalytic reagents can offer improve efficiency and environmental benefits. Still, they must be carefully matched to the application—much like how an electric screwdriver is more effective than a manual one, but only when equipped with the correct bit. In all cases, greater selectivity should remain a key consideration when choosing reagents.
References
- 12 Principles of Green Chemistry – ACS
- 12 Design Principles of Green Engineering – ACS
- Sheldon, R.A. – E-factor and atom economy
- Catalysis in sustainable chemistry
- Types of Catalysts – IntechOpen
Resources