Chemical Characterization of Asphaltenes

Depending on the origin of the crude oil from which they are precipitated, asphaltenes can exhibit wide differences in composition and structure. The amount and length of the alkyl side chains as well as the number of aromatic rings may change in such a way that the variations of molecular weight and aromaticity factor of asphaltenes are notorious (Ancheyta and Speight, 2007 Ancheyta et al., 2010). 

Asphaltene molecular weight distribution and heteroatom content are both of great importance to design catalysts with suitable properties to process these heavy materials, i.e., optimal pore size distribution to allow the complex molecules to access the catalytic sites with minimal diffusion limitations and to enhance metal retention capacity. 

This section compares the properties of asphaltenes precipitated from various crude oils with API gravity ranging from 10° to 33° (Leyva et al., 2012). 

FIGURE 1.2 Average structure of continental-type and archipelago-type asphaltenes. (Adapted from Zhao, S. etaL,Fr/c/, 80(8), 1155, 2001 Sheremata, J.M. et ah. Energy Fuels, 18(5), 1377, 2004.) 

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Demirba , A. 2002. Physical and chemical characterizations of asphaltenes from different sources. Petrol. Sci. Technol. 20(5-6) 485-495. 

Leyva, C., Ancheyta, J., Berrneco, C., MUlan, M. 2012. Chemical characterization of asphaltenes from various crude oils. Fuel Proc. Tech, (submitted). 

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