AL – Mansuriya gas fields associated liquid and its role to increase the potential capacity of gasoline fuel in Daura oil refinery

Abstract

Hydrotreating processing is commonly used to remove platforming catalyst poisons from straight run or cracked naphthas prior to charging to the platforming Process unit. It can be seen that the primary function of the naphtha Hydrotreating Process can be characterized as a “Clean up” Operation. The catalyst used in the Naphtha Hydrotreating Process is composed of an alumina base impregnated with compounds of cobalt or nickel and molybdenum. The catalyst is insensitive to most poisons which affect dehydrogenation reactions. A relatively high percentage of carbon on the catalyst does not materially affect its sensitivity or selectivity. Volumetric recoveries of products depend on the sulfur and olefin contents [1].

The Naphtha Hydrotreating Process is a catalytic refining process employing a selected catalyst and a hydrogen-rich gas stream to decompose organic sulfur, oxygen and nitrogen compounds contained in hydrocarbon fractions. In addition, hydrotreating removes organo-metallic compounds and saturates olefinic compounds.

Organo-metallic compounds, notably arsenic and lead compounds, are known to be permanent poisons to platinum catalysts. "The complete removal of these materials by Hydrotreating processing gives longer catalyst life in the platforming unit.

Sulfur, above a critical level, is a temporary poison to platforming catalysts and causes an unfavorable change in the product distribution. Organic nitrogen is also a temporary poison to platforming catalyst. It is an extremely potent one, however, and relatively small amounts of nitrogen compounds in the Platformer feed can cause large deactivation effects, as well as the deposition of ammonium chloride salts in the platforming unit cold sections.

Oxygen compounds are detrimental to the operation of a Platformer. Any oxygen compounds which are not removed in the hydrotreater will be converted to water in the platforming unit, thus affecting the water/ chloride balance of the platforming catalyst. Large amounts of olefins contribute to increase coking of the platforming catalyst. Also, olefins can poly­merize at platforming operating conditions which can result in exchanger and reactor fouling.

The Naphtha Hydrotreating Process makes a major contribution to the ease of operation and economy of platforming. Much greater flexibility is afforded in choice of allowable charge stocks to the platforming unit. Because this unit protects the platforming catalyst, it is important to maintain consistently good operation in the Hydrotreating Unit.

In addition to treating naphtha for Platformer feed, naphthas produced from thermal cracking processes, such as delayed coking and visbreaking, are usually high in olefinic content and other contaminants, and may not be stable in storage. These naphthas may be hydrotreated to stabilize the olefins and to remove organic or metallic contaminants, thus providing a marketable product.