Electrically heated: steam cracker
Fossil fuels represent the largest sources of CO2 in the chemical industry because chemistry requires energy.
To split naphtha into olefins and aromatics for further processing, BASF’s steam crackers need to reach a temperature of 850°C.
Until now, the cracker’s furnaces have been fossil-fired, meaning they are operated with natural gas.
If we could operate these crackers with renewable electricity instead, this would reduce the CO2 emissions by up to 90 percent.
An interdisciplinary team is therefore working on developing a fundamentally new furnace concept.
The idea is to heat the crackers with an electrical resistance heater, or e-furnace.
If this heating system is powered by renewable wind and solar energy, the high temperatures required could be achieved with nearly zero CO2 emissions.
CO2-free hydrogen production: Methane pyrolysis
The chemical industry needs large quantities of hydrogen. For instance, BASF uses it as a reactant for ammonia synthesis.
Because hydrogen is indispensable for carrying and storing energy in numerous sustainable future applications, it will continue to grow in importance.
Steam reforming is currently the most important industrial-scale procedure for producing hydrogen from natural gas or coal. However, this process releases considerable quantities of CO2.
As part of its Carbon Management program, BASF is working together with cooperation partners in a project funded by the Federal Ministry of Education and Research (BMBF) to develop a new process technology for producing clean hydrogen from natural gas – methane pyrolysis, in which methane or natural gas, which mainly consists of methane, is split directly into its components of hydrogen and solid carbon.
The process uses comparatively little energy and, if it is run using electricity from renewable resources, is even CO2-free.
The technical feasibility at lab level has already been examined; an initial reactor concept with a moving carbon bed has been tested at lab scale and samples of resulting solid carbon produced.
Fundamental research must now be carried out into the pyrolysis process itself, the reactor design and the heating concept.
Heat-resistant materials are an additional focus. Currently, we are building a test facility at the Ludwigshafen site, which is around 15 m high. The aim is to create a stable functioning test reactor. The test facility is to be completed and put into operation in 2020.
It is still unclear how the granular carbon from our pyrolysis will be used. In general, there are numerous markets for solid carbon, especially for high purity carbon.
Customers include, among others, the aluminium, steel, tyre and construction industries.
Storage is also conceivable in principle, because our pyrolysis carbon is not a hazardous substance and can be stored in a stable manner.
The various approaches to the use or storage of pyrolysis carbon are being investigated in the current project.
Biomethane derived from biogas can also be used as the starting material of methane pyrolysis.
The resulting pyrolysis carbon could be made available as climate-neutral carbon to other industries that, for example, have limited possibilities for emission reduction.
If such a bio-based carbon is stored or permanently bound, this represents a so-called “carbon negative technology”.
The various possibilities are currently being investigated. Only when these questions have been answered can a pilot plant be set up. If it operates successfully, commercial methane pyrolysis could be pursued.
CO2-free production: Methanol
Methanol is an important starting material for many BASF products. As part of the Carbon Management research program, BASF scientists are now working on a new climate-friendly process to produce this important basic chemical.
The aim is to not just reduce CO2 emissions, but to emit no CO2 throughout the entire process. Nearly 100 years after the first industrial-scale production using BASF’s high-pressure process, we are now writing a new chapter in the history of methanol with this project.
Typically, methanol is produced from syngas. Until now, syngas has been primarily obtained from natural gas via a combination of steam and autothermal reforming.
In the new BASF process, the syngas is replaced by a partial oxidation of natural gas, which does not cause any CO2 emissions.
While the process steps methanol synthesis and distillation can be carried out nearly unchanged, ingenuity was required to address the merging and processing of the resulting waste gas streams. First, they are incinerated with pure oxygen.
Gas scrubbing is then used to completely remove the CO2 from the flue gas. To ensure that the carbon contained in the gas is not lost and that it can be used again for methanol synthesis, the captured CO2 is fed back into the beginning of the process.
This does, however, require additional hydrogen, which BASF also aims to produce without any CO2 emissions, for example, via methane pyrolysis, which is also being developed in the research program.
Key components of the new methanol synthesis process were tested for nearly a year at BASF’s subsidiary hte GmbH in Heidelberg.
The project team expects it will be around 10 years before this new process is carried out in an industrial-scale plant.
CO2-free synthesis: olefins
As a central, high-volume intermediate, olefins represent an especially important area where BASF is looking to develop new low-emission processes.
Currently, olefins are produced by cracking naphtha at temperatures of up to 1000°C in the steam cracker. This process creates significant CO2 emissions.
By switching from naphtha to methane and using an electrically heated reformer furnace, these emissions could be avoided.
Working in cooperation with Linde, BASF researchers were able to develop an entirely new, powerful catalyst system that enables syngas to be produced through dry reforming of methane with CO2. This syngas can be transformed into olefins via an intermediate step of dimethyl ether (DME).
Compared to naphtha, methane has a slightly higher energy content and contains more hydrogen. As a result, the olefins production process can use not only the CO2 produced in the DME step but also additional CO2.
In this way, the process becomes CO2-neutral and because of the use of additional CO2, it can even be a “carbon sink,” meaning overall it binds CO2, provided that the electrical reformer furnace is powered with renewable energy and no emissions are generated by the heating process.
The research and development is currently focusing on the process of dry reforming itself. The combination with electrical heating of the reformer is an option for the future, depending on the progress of the development of the electrically heated steam cracker.
Refs
Innovations for climate-friendly chemical production
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