The impact of solid additives on the apparent solubility of hydrogen in petroleum fractions and model hydrocarbon liquids

Abstract

Hydrogen is a key reagent in the petroleum and petrochemical industry. Thus, the intrinsic solubility of hydrogen in organic liquids of industrial interest is an important parameter for process design and process modeling. The existing hydrogen solubility data base for industrial fluids is limited and does not account for the potential impact of trace additives such as clay and catalyst fines, on the apparent solubility of hydrogen in these media. Such finely divided solids present large solid–liquid interfaces where hydrogen can sorb in competition with the liquid media leading to an inadvertent overestimation of the intrinsic hydrogen solubility. In this work, the effect of common solid additives on the apparent solubility of hydrogen in hydrocarbon liquids has been investigated. Hydrogen solubilities in hexadecane, tetralin, and light and heavy virgin gas oils were measured with and without the solid additives, including a commercial hydrotreating catalyst (CHC), used CHC, CHC support, alumina, silica and carbon black. The measurements were made under a wide range of conditions: with upper limits of 380°C and 12.0 MPa. These solids all sorb hydrogen but only silica, used hydrotreating catalyst and hydrotreating catalyst support sorb significant amounts of hydrogen in the presence of liquid hydrocarbons. These latter three materials, present in many industrial heavy oil samples raise the apparent solubility of hydrogen in these liquids. The presence of such solids is rarely reported even when present. Thus, two sets of hydrogen solubility in heavy oil data exist in the literature — data where hydrogen solubility is over stated due to the presence of such solids and data that are unaffected.