Effect of sulfur-containing acids on the penetration and softening point of asphalts obtained from acid sludge

Thin-film cracking of acid tars

“…Duration of the TFC AT process. According to the thermal and kinetic data, the degradation of sulfonic acids in AT takes place in the temperature interval of 120-350 о С and the cracking of high molecular mass AT components resins, asphaltenes, and oils occurs at 400-500°С [7][8][9]. In terms of kinetics, sulfonic acids under the conditions of heating of the thin film of liq uid AT decompose entirely well below the onset crack ing temperature of higher hydrocarbons.…”

“…OF ACID TAR Since the heating of a thin liquid film of acid tar on the heated working surface of the reactor and the ther mal degradation of hydrocarbons occur simulta neously and the cracking of AT components in the liq uid phase follows the first order rate law [7][8][9], the thin film cracking of acid tar can be described as fol lows.…”

“…At 200-350 о С, the reactions of thermal degradation of sulfonic acids and desulfurization of asphaltenes and resins yielding a certain amount of liquid hydrocarbons mainly pro ceed in AT, whereas the processes of cracking of high molecular mass compounds to asphaltic products and volatile hydrocarbons occur above 400 о С. To preclude the low temperature hydrolysis of sulfonic acids and the catalytic action of sulfuric acid on the thermal deg radation of the AT components, an AT sample washed of sulfuric acid and soluble sulfonic acids with water was used in the kinetic studies [9][10][11]. The investiga tion of the sulfuric acid effect on the thermal cracking of AT and the cracking of benzenesulfonic acid [9] showed that sulfuric acid takes part in redox reactions with components of the reaction mixture and also acts as a reactant and catalyst.…”

“…The cracking of higher petroleum hydrocarbons follows the first order rate law at a small depth of thermal decomposition regardless of the component nature [2,8]. The basic descriptive kinetics of acid tar cracking under static conditions was studied in [9][10][11]. At 200-350 о С, the reactions of thermal degradation of sulfonic acids and desulfurization of asphaltenes and resins yielding a certain amount of liquid hydrocarbons mainly pro ceed in AT, whereas the processes of cracking of high molecular mass compounds to asphaltic products and volatile hydrocarbons occur above 400 о С.…”

“…To preclude the low temperature hydrolysis of sulfonic acids and the catalytic action of sulfuric acid on the thermal deg radation of the AT components, an AT sample washed of sulfuric acid and soluble sulfonic acids with water was used in the kinetic studies [9][10][11]. The investiga tion of the sulfuric acid effect on the thermal cracking of AT and the cracking of benzenesulfonic acid [9] showed that sulfuric acid takes part in redox reactions with components of the reaction mixture and also acts as a reactant and catalyst. In the presence of sulfuric acid, the cracking of sulfonic acids proceeds at a high rate and is accompanied by the formation of sulfur dioxide, water, and tars; in the absence of sulfuric acid, the products of AT cracking under static conditions include free sulfur, sulfur dioxide, and hydrogen sul fide [4].…”