Simplification of Heavy Matrices by Liquid–Solid Extraction: Part II—How to Separate the LMW, MMW, and HMW Compounds in Asphaltene Fractions for V, Ni, and S Compounds

Abstract : A method of sequential liq.-​solid extn. (leaching) has been developed to ext. the V, Ni, and S compds. present in asphaltenes (n-​C7) according to their mol. wt. distribution. For the high-​mol.-​wt. (HMW) compds., 2 new families of compds. were extd., labeled as HMW1 and HMW2, where the latter was smaller than HMW1, and together represented ∼85​% of the asphaltene mass according to the mass balance obtained after the extns. The compds. assocd. with HMW1 were asphaltenes that were insol. in hot DMF, while the compds. assocd. with HMW2 were sol. in DMF but insol. in the 2nd leaching step based on hot acetone. The 3rd family of obtained compds. was the medium-​mol.-​wt. (MMW) compds., which were sol. in hot acetone but insol. in MeCN (ACN)​. The last fraction to be obtained was the low-​mol.-​wt. compds., which were sol. in ACN. The results reported here represent a new method that allows the extn. of different types of aggregated asphaltenes according to their mol. wts. With respect to the temp. and no. of extn. steps, an increase in both parameters increased the extn. efficiency.