Fuel, Vol.180, 284-291, 2016
Comparison of the metal-organic framework MIL-101 (Cr) versus four commercial adsorbents for nitrogen compounds removal in diesel feedstocks
Performance of metal-organic framework MIL-101 (Cr) to remove, through adsorption, organic nitrogen (N-) compounds from straight run gas oil (SRGO) and straight run gas oil/light cycle oil (SRGO/LCO) mixtures was compared against that for four commercial adsorbents: silica gel, Selexsorb (R) CD, Selexsorb (R) CDX and activated carbon in batch and fixed-bed experimental set-ups. For fixed-bed tests, MIL-101 (Cr) was pelletized using carboxymethylcellulose as agglomerant. Room temperature batch data at equilibrium, showed that MIL-101 (Cr) has, by far, the highest adsorption capacity, following both Langmuir and Freundlich models for the adsorption of N-compounds. Kinetic data show that MIL-101 (Cr) has also the fastest adsorption rate treating SRGO under room conditions. Lumped kinetic analysis showed that adsorption is described by a pseudo second-order rate equation. Correspondingly, flow fixed-bed data showed that MIL-101 (Cr) achieved a higher adsorption loading of N-compounds than commercial adsorbents, being the flow rate and Nitrogen content in feed the main variables affecting the cycle length before adsorbent regeneration was needed. Additionally, MIL-101 (Cr) showed a good stability, maintaining its initial adsorption capacity after 300 regeneration procedures (from 90 to 85%). It is expected an useful life in industrial application of at least 1000 cycles. According to the aforementioned, MIL-101 (Cr) confirmed to be a promising material for the adsorption of N-compounds from middle distillates as a pretreatment step toward ultra low sulfur diesel production. (C) 2016 Elsevier Ltd. All rights reserved.