Purification of nitrogen containing feedstreams

Gerrard, M.L., 2001. Purification of nitrogen containing feedstreams. PhD, Nottingham Trent University.

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Organic nitrogen present in crude oil must be removed before many refining processes can be performed. The continuous drive towards more efficient refineries, combined with a movement toward cleaner, less environmentally polluting fuels is increasing the pressure on existing nitrogen removal technologies. Traditionally nitrogen is removed by hydrotreating over a Co (Ni)-Mo based catalyst which, in the case of naphtha, lowers the nitrogen content from ~20 ppm to ~0.5 ppm. Further reduction is very difficult to achieve. The use of an adsorbent may be a solution to this problem. With a catalytic process each incremental decrease in nitrogen concentration becomes exponentially more difficult and expensive, whereas with an adsorbent the reverse is true. The ideal adsorbent should be able to selectively adsorb organic nitrogen compounds at a reasonable operating temperature without altering the remaining hydrocarbon stream.

In this work potential adsorbents have been studied using a model system of 10 ppm pyridine in heptane. Experimental conditions have been chosen which approximate to an industrial application. The primary characterisation technique used was FTIR of adsorbed pyridine, in addition to N2 adsorption, XRD and TEM.

Supported metal sulfates and modified aluminas were found to have low adsorption capacities at the operational temperature of 200 °C; the most effective samples adsorbing 0.2 - 0.3 wt % pyridine. Amorphous silica aluminas have adsorption capacities of up to 0.6 wt %. MCM-41 materials have been shown to have adsorption capacities up to 1.0 wt % and have successfully been regenerated and re-used with only a 10 % reduction in capacity. Zeolite X, mordenite, and ZSM-5 have also been studied. Zeolites in the Na+ form are ineffective, either because the Na+ acid sites are not strong enough to retain pyridine under the experimental conditions or because of selective coking. Zeolites in the H+ or Cu+ forms have high adsorption capacities: up to 2.5 wt %

Item Type: Thesis
Creators: Gerrard, M.L.
Date: 2001
ISBN: 9781369316742
Divisions: Schools > School of Science and Technology
Record created by: Linda Sullivan
Date Added: 30 Sep 2020 12:58
Last Modified: 13 Sep 2023 12:24
URI: https://irep.ntu.ac.uk/id/eprint/41026

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