In Brazil, the number of pig farms that produce biogas has grown rapidly in recent years. This has been happening due to the possibility of producing electricity using biogas as fuel to power electric generators. Nowadays Brazil produces 1.4 billion Nm3/year, and this represents about 1.5% of the production potential. Although 1.5% seems to be a small share, it represents 8.3% of the electric energy produced in Brazil in 2019.
One of the main drawbacks in this process is the corrosion of the gas pipelines, engine, and turbine, caused by hydrogen sulfide (H₂S) present in the biogas causing a high maintenance cost. Recently, we have developed a new efficient and low-cost process to remove the H₂S, based on a new carbon catalyst on a lab-scale (efficiency of 94% in the H₂S oxidation). In this work, we describe the scaleup of this technology.
The first step was to produce an active catalyst replacing the high purity chemicals with commercially available industrial raw materials. A new series of catalysts were produced using industrial grade silica, quaternary ammonium salt, and Fe₃⁺ salt with an important change, replacement of acetonitrile (more expansive and toxic carbon source) to bioethanol with performances similar (92% H₂S conversion) to the original catalyst (94%).
Working with non-analytical reactants brings lots of new challenges to the research. To improve this rate and produce a catalyst that can be synthesized in large amounts a wide variety of tests have been done. After running through 15 synthesis a catalyst capable of oxidizing 92% of the H₂S present in a solution.
The second step was to design and built a reactor to carry out a continuous CVD to produce 15 kg_catalyst/h. This reactor was installed, and the first reactions carried out and are currently under optimization. The third step is to test the catalyst production and validate the application in a local farm.

Image of the reactor design to scale-up the catalyst production by 100.000x

Rochel Lago

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