High-pressure processes for sustainable chemical production

High-pressure processes for sustainable chemical production

Chemical processes develop in different ways and with many different output products depending on a variety of conditions such as temperature, pressure, solvent and added catalysts – as well as on innumerable potential combinations of these factors. By finding optimal ways of executing chemical processes, Marco Maschietti can help companies reduce costs, maximise yield – and find entirely new, more sustainable ways of producing products that we use in large quantities in our everyday lives.

Lignin: A renewable source of everyday chemicals

- “I am currently working on a project focusing on converting lignin, a natural biopolymer that is one of the basic structural materials in many plants, into a range of chemicals that are currently being produced from petroleum. Vast amounts of lignin will be available in the future as a by-product of new biomass-based processes, but at the moment this by-product is under-utilised. It has, however, the potential of being converted into value-added products. This by-product is typically made available either dispersed in water or wet, and therefore it is particularly convenient to develop chemical processes that can convert it operating in water, so as to avoid the energy cost of drying” Marco Maschietti explains.

- “Our work focuses on finding new ways of converting lignin in water at very high pressure and high temperature, maybe between 150 and 400 degrees Celsius, but keeping the water in its liquid state because of the high pressure. We are in essence cooking the lignin to break it into smaller atoms, and when we dissolve lignin in water at these high temperatures, the structure of the polymer breaks and we get many small molecules. In addition, the process happens very fast under these conditions, and depending on the exact pressure and temperature settings, as well as which catalysts we add to the process, we can produce a range of very valuable chemicals from the lignin” he adds. Historically, the production of vanillin, which we know from our everyday lives in the shape of vanilla aroma in products like ice cream, is the only lignin-to-chemical process that has reached commercialisation, but there is a great potential for producing a much wider range of chemicals, including building blocks for chemical products currently produced from petroleum, fuel additives, disinfectants, fragrances, etc. By producing these from a renewable source instead of from petroleum, the production will be much more sustainable and environmentally friendly. At the same time, the biomass used in bio-refineries can be utilised to an even higher degree than it is now.

- “The major advantage of using lignin as a source of these chemicals instead of petroleum is that we have access to enormous amounts of lignin from sustainable and renewable sources. It is created as a by-product from biomass in bio-refineries, but the lignin is usually just burned to produce energy. However, there is a shared consensus among researchers that if the biomass and bio-refinery industry is to be more profitable and competitive, we need to do something with the lignin too; something that will give it a much higher value than just burning it to produce energy” Marco Maschietti says.

A revolution of the chemical industry

In order to study and refine the conversion of lignin, Marco Maschietti has collaborated with a specialist company to develop the design for a custom-made high-pressure, high-temperature chemical reactor. This new reactor is now available in the laboratories of the Section of Chemical Engineering in Esbjerg and here, Marco Maschietti can try out various combinations of pressure, temperature, catalysts and solvents at a higher level of accuracy compared to typical serial reactors commercialised for laboratory use. The new reactor thus allows for higher accuracy and results which are closer to those that could be obtained at pilot scale, and therefore more reliable.

“We are still quite a way from being ready to scale the processes to an industrial level, but our chemical reactor enables us to study the different aspects of the chemical reaction in order to improve the process,” he explains and adds: “At this point, we have shown at a laboratory scale that we are able to produce these chemicals. Now, we need to refine them further, for example to avoid by-products from the lignin conversion that either have no value or may do harm to the molecules that do have value.”

He is convinced that the emergence of a lignin-based chemical industry will happen within the next couple of decades – and that it will mean a major change for the way we view the chemical industry.

- “We are still at the very beginning of this process and need to do many more years of lab work, including work in a demo and test facility that is larger than our test reactor here, but once we show that a chemical production like this is feasible at a large scale – and can be competitive with the petro-chemical industry – we can prove that this kind of industrial facility is worth investing in. I am convinced that it will happen at some point, and it will not be an exaggeration to say that the full development of lignocellulosic bio-refineries will be a revolution of the chemical industry. It will be an entirely new but very important direction for this industry – you can compare it to the birth of the petro-chemical industry when it developed from petroleum production to all the fuels, fertilisers, chemicals and other products we know today” he emphasises.

Optimising offshore gas and oil production

Marco Maschietti’s expert knowledge on high-pressure chemical processes is also brought into use in an industry that some may at first glance see as oppositional to his lignin research; namely the oil and gas industry, where he works on optimising the separation of water, oil and gas at offshore platforms.

“The so-called ‘separation train’ takes place when the fluid from underground petroleum reservoirs reaches the offshore platform topside. Typically, the fluid arrives at the platform at high pressure, maybe 40 to 60 bars, and at a moderate temperature of 40-60 degrees Celsius. One of the first processes at the platform is to reduce the pressure of the fluid and separate water, oil and gas before they are transported onshore for further processing” Marco Maschietti explains.

In a project funded by the Danish Hydrocarbon Research and Technology Center, Marco Maschietti is working on how to optimise the operating conditions of this process.

- “The reduction of pressure is usually done over two or three stages, but there are millions of possible ways to do it. Is it best to go from, say, 60 to 40 to 1 bar, or is it best to operate the separators at 30, 15 and 1 bar?” Marco Maschietti says.

- “Optimising the separation train is crucial, because it determines how effective the separation of water, oil and gas is – and how pure the products are. For instance, we want to separate the ethane and methane molecules – the natural gas – from the oil, but we want to keep the components that have 5-6 carbon atoms or more in the oil. And we want to keep intermediate components like propane in the oil – but not in too large amounts, because then the oil gets unstable” he explains.

Comparing millions of potential scenarios

Traditionally, the parameters for the separation train were determined by experienced engineers who had defined a number of rules of thumb for the best output, but with the advent of processing computers and the possibility of using simulation software, the researchers can analyse and optimise the potential separation processes in much finer detail.

“We study the processes that are described in the literature within the field by running them through customised simulation programmes to analyse the effect and efficiency of the different setups – and to determine how and where they can be optimised” Marco Maschietti explains.

“What we aim at is to show potential optimisation margins – including maximising the production of oil, minimising the energy spent on the different processes that are performed offshore, and increasing the purity of the oil and gas that are the result of the separation train. The aim is of course to cut overall costs and keep the price of oil competitive, but it is also to reduce for instance the energy used during these processes to make them more environmentally friendly. The less processing we need to do from oil well to end user, the lower the monetary and environmental costs of the oil production will be” he adds. At this point, the researchers have been able to highlight some possible margins of improvement that they can present to the oil and gas industry and compare to actual working setups at the companies’ offshore platforms.

- “Whether or not our results will be implemented will depend on how feasible the realistic margin for improvement is – in other words, whether the oil and gas industry find it feasible to invest in further research and implementing our results. If the industry gives us the go-ahead for further investigation, we might see our results implemented within a fairly short timeframe, as the industry will not need to build new facilities but rather just change the parameters of existing processes to adjust and optimise them” Marco Maschietti says.

Competitors – but also complimentary industries

In Marco Maschietti’s opinion, the two industries that he works with may be competitors on the market, but that does not mean they cannot co-exist for many years to come.

- ”You could say that the two areas of my work seem oppositional at first glance, but I do not at all see it that way. On the contrary, I see them as complimentary industries. We will need oil and gas in our society for many years to come, but at the same time we need to develop the biomass industry and the processes for producing chemicals from renewable sources. The two industries will be running alongside each other, but in both cases we need to focus on increasing the efficiency and optimising the use of resources. This will, in the end, work towards a more sustainable and environmentally friendly chemical industry” Marco Maschietti finishes.