Green chemistry

Green chemistry has been rapidly gaining exposure in the chemical manufacturing sector as it continues to influence alternative greener and more sustainable technologies in a bid to help tackle the impact that the chemical industry has on our environment.

For considerable time, the imprecise and highly subjective goal of conducting sustainable chemistry has been forefront in research and development. The ability to discern what this means in an industrially relevant, and commercially implementable at manufacturing scale, sense is quite difficult.

However, forming an intrinsic factor of this objective is the highly detailed framework of green chemistry. Which has been receiving growing recognition for its 12 core principles that will enable businesses to continue manufacturing in way that is both achievable and maintainable, whilst being more sustainable.

Chemical engineering is predominantly focused on the design and build of facilities and processes that generate product, in commercial quantities, from raw materials. Doing this in a sustainable manner involves the design of chemical processes which are less hazardous, less demanding of resources and with minimal waste generation.

The 12 principles of sustainable chemistry

Understanding the 12 core principles of green chemistry are key to comprehending the breadth of the available opportunities to think greener. Their application can reduce the considerable strain that conventional chemistry places on the environment and available energy resources.

Originally published in 1998 by Paul Anastas and John Warner, the principles are a framework designed to target making chemicals, processes and products more sustainable.

These principles in short, are:

To prevent waste entirely, which will effectively remove the requirement for costly treatments of chemical waste materials and the remediation of contaminated environments.

To maximise atom economy and the number of reactant atoms which are incorporated into the final product rather than forming potentially hazardous waste by products.

To opt for less hazardous synthetic methods which generate substances that are of minimal or zero harm to the environment.

To design safer chemical products which preserve function while minimising toxicity.

The use of solvents and other auxiliary substances should be eliminated where possible. Should they need to be used, they should be as safe as possible for humans and the environment.

Design with energy efficiency in mind, by removing the requirement for extreme temperatures or pressures and opting for ambient process alternatives.

Where possible, syntheses should make use of feedstocks (starting materials) that are renewable rather than those which will become depleted with ongoing use.

Reduce or eliminate the use of chemical derivatives which require additional reagents and process steps, thereby requiring more energy and risking the generation of more waste.

Incorporate catalytic reagents to minimise the consumption of stoichiometric reagents.

Design with degradation in mind so that once a product’s function is fulfilled, it breaks down into harmless degradation products which do not persist in the environment.

Develop real time analysis to provide in-process feedback which can enable controlled monitoring of potentially generated hazardous products prior to their formation.

Conduct safer chemistry for accident prevention by utilising substances that are designed to minimise the risk of accidents including releases, explosions, and fires.

How can flow technology implement these principles

These initiatives can be hard to implement. Often, they require assessing the entire life cycle of the chemical product to evaluate where in its lifetime adjustments can be made. This includes the design, manufacture, use and disposal of the product.

As Ben Franklin once said, ‘an ounce of prevention is worth a pound of cure’. This is inherent in what the green chemistry principles aim to achieve; reducing environmental hazards at their source in order to avoid any clean ups.

There are many examples in chemical manufacturing that ably demonstrate the application of green chemistry, from substituting hazardous sorbents with non-hazardous ones, to opting for continuous rather than batch manufacturing.

Continuous flow makes a promise to green chemistry

The approach of continuous manufacturing in various industries is ultimately a more sustainable choice than counter options because it readily implements changes that abide by several of the core principles.

  1. atom economy
  2. reduced solvent use
  3. safer chemistry

Continuous flow employs both efficient mixing and regular heat transfers which makes controlling a reaction much easier. This provides the opportunity to run more concentrated reactions, thus reducing the percentage of solvents in the total reaction volume. Using more reagents and less solvents inherently means that atom efficiency is improved.

Pumping such reagents from starting tanks through to small reactors and collecting product at the outlet simultaneously, means there is a smaller working volume of hazardous materials in the reactor at one time. Unlike batch where all materials are added into a singular much larger rector at once. Ultimately, the smaller the reactor, the safer the chemistry.

  1. energy efficiency
  2. real-time analysis

The key with a smaller, continuous reactor is that the downtime required is minimal in comparison to that of a batch counterpart. The total utilisation of a batch reactor is intrinsically limited, it requires rest time which involves cleaning, heating up and cooling down. All steps of which require human intervention and energy consumption. Flow reactors are designed to run continuously for prolonged periods of weeks or months, resulting in a plant productive capacity that is orders of magnitude higher than with a batch reactor and producing more material for the energy consumed than compared to batch.  

This steady state that flow reactors are designed to reach is determined by the residence time and reactor volume. For example, if the working volume of the Coflore RTR is 100 litres with a 5-minute residence time, it can process 1,200 L/hour indefinitely, and with minimal intervention.

Manufacturing in a way where the output remains constant and predictable greatly reduces the number of operator steps required to be. Restricting hazardous reaction steps within an inherently smaller working reactor volume means that operation is intrinsically safer, particularly for larger production runs.

Bringing green chemistry to your manufacturing with Coflore

Implementing continuous manufacturing brings huge and wide-ranging benefits, but we’ve found that companies often prefer to stick to what they know. Knowledge barriers in the continuous flow industry are a prevalent hesitation along with the logistical hurdles of integrating continuous production, process measurements, control systems and more into an existing facility.

Tackling these kinds of viewpoints requires providing assistance and expertise at all stages of the transition. Especially when a continuous process involves more than just benchtop feasibility. Working towards a flow process at pilot plant scale and manufacturing scale can be conducted from the AM Technology headquarters, located in the UK, with the help of a multidisciplinary team which includes Flow Chemists and Electrical, Mechanical and Chemical Engineers.

At AM Technology, we can help with your chemical processes and facilitate your journey to greener chemistry, and a more sustainable business.

Think greener, think Coflore!