Glycerin-based adsorbents for the separation of ethane and ethylene

The separation of ethane from a mixture of ethane/ethylene is a large scale process. Therefore, if adsorption is to be considered for this separation, besides the amounts adsorbed and selectivity type and values, the adsorbent also needs to have a relatively low cost. Considering the large volume of glycerol coming from biodiesel production it is also important to find new applications for this substance. With this goal, we synthesized a series of glycerin-activated carbons via a two-step procedure involving carbonization followed by chemical activation. The prepared adsorbents presented high surface areas, ranging from 1166 to 2150 m2 g−1 and have pore volumes between 0.63 and 1.03 cm3g−1. The glycerin-activated carbons were evaluated as adsorbents for adsorption-separation of ethane and ethylene. All the adsorbents showed to be ethane selective, that is to say, the materials exhibited higher adsorption capacity of ethane than ethylene. This is a key factor, related with the nature of the materials surface, for their application in the separation of ethylene from a mixture of ethane/ethylene. Ethane adsorption capacity was in the range 8.92–14.81 mmol g−1. Therefore, a low-cost by-product of biodiesel production – glycerin – can be transformed in a material that has promising properties for adsorption-separation of C2H6/C2H4.