Process for obtaining the hydrocarbon from a hydrocarbon-rich gel

The present invention relates to a process for obtaining the hydrocarbon from a hydrocarbon-rich gel based on an ionic surfactant by treatment of the gel with a laminar mineral.

The present invention relates to a process for obtaining the hydrocarbon 
from a hydrocarbon-rich gel by treatment with a laminar mineral. 
BACKGROUND OF THE INVENTION 
Storage and transportation of liquid hydrocarbons, for example fuels, via 
road, rail and on the waterways present a considerable potential hazard. 
Thus, for example, the high flammability and explosiveness in mixtures 
with air has led in the past to serious accidents which have caused 
considerable damage. Serious ecological damage moreover is constantly 
arising due to fuels being discharged from leaking storage or 
transportation tanks. 
It is already known that hydrocarbons can be converted into so-called 
hydrocarbon-rich gels. These are understood as meaning a system which 
consists of polyhedrons which are formed from surfactant and are filled 
with hydrocarbon, water forming a continuous phase in the narrow 
interstices between the polyhedrons (Angew. Chem. 100 933 (1988) and Ber. 
Bunsenges. Phys. Chem. 92 1158 (1988)). 
Hydrocarbon-rich gels are distinguished by the occurrence of a yield value. 
This yield value is reached when the gel no longer withstands a stress 
imposed on it (shear, deformation) and starts to flow. Below the yield 
value, the gel structures have the properties of solids and obey Hooke's 
law. Above the yield value, in the ideal case, the system is equivalent to 
a Newtonian fluid. This means that although hydrocarbon-rich gels can be 
pumped in a simple manner, because of their properties as solids they 
cannot flow in the state of rest. 
Provided that a process is available which allows the hydrocarbon to be 
recovered, hydrocarbon-rich gels are an outstanding form of storage and 
transportation. They cannot be discharged from defective storage or 
transportation tanks and danger to the environment is virtually excluded. 
It has now been found, surprisingly, that the structure of hydrocarbon-rich 
gels which contain ionic surfactants can be broken down with the aid of 
laminar minerals and the hydrocarbon can be recovered. 
SUMMARY OF THE INVENTION 
The present invention thus relates to a process for obtaining the 
hydrocarbon from a hydrocarbon-rich gel based on an ionic surfactant by 
treatment of the gel with the laminar mineral which carries opposite 
charges to the surfactant. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention thus relates to a process for obtaining the 
hydrocarbon from a hydrocarbon-rich gel based on an ionic surfactant by 
treatment of the gel with the laminar mineral which carries opposite 
charges to the surfactant. 
Hydrocarbon-rich gels which are particularly suitable for the process 
according to the invention consist of 70 to 99.5% by weight of 
hydrocarbon, 0.01 to 15% by weight of ionic surfactant and 0.49 to 15% by 
weight of water. 
Hydrocarbon-rich gels which are expecially suitable for the process 
according to the invention consist of 80 to 99.5% by weight of 
hydrocarbon, 0.01 to 5% by weight of ionic surfactant and 0.49 to 15% by 
weight of water. 
Hydrocarbons which are particularly suitable for the process according to 
the invention are n-pentane, n-hexane, n-heptane, n-octane, n-nonane, 
n-decane, n-dodecane, n-tetradecane, n-hexadecane, cyclohexane, 
cyclooctane, benzene, toluene, kerosine, leaded and lead-free petrol, 
heating oil, diesel oil and crude oil. 
The hydrocarbon-rich gel can contain cationic or anionic surfactants. 
Preferred cationic surfactants are quaternary ammonium compounds of the 
formula 
##STR1## 
wherein R.sup.1 denotes alkyl having 10 to 22 C atoms, 
R.sup.2 denotes alkyl having 1 to 12 C atoms or benzyl, 
R.sup.3 and R.sup.4 independently of one another denote hydrogen or methyl 
and 
X.sup..crclbar. denotes Cl.sup..crclbar., Br.sup..crclbar. or CH.sub.3 
SO.sub.4.sup..crclbar. ; 
fatty amines, such as, for example, coconut-fatty amines, lauryl-fatty 
amine, oleyl-fatty amine, stearyl-fatty amine, tallow-fatty amine, 
dimethyl-fatty amine or primary alkylamines having pure chains of 8 to 22 
C atoms; ammonium borate betaine based on didecylamine; 
stearyl-N-acylamido-N-methyl-imidazolinium chloride of the formula 
##STR2## 
and alkenylsuccinic acid derivatives of the formulae 
##STR3## 
wherein R in each case denotes iso-C.sub.18 H.sub.35 or polybutenyl. 
Preferred anionic surfactants are soaps of the formula 
EQU R--CH.sub.2 --COO.sup..crclbar. Na.sup..sym. 
wherein R denotes a hydrocarbon radical having 10 to 20 C atoms; 
alkanesulphonates of the formula 
##STR4## 
wherein R and R' denote alkyl radicals having together 11 to 17 C atoms; 
alkylbenzenesulphonates or -sulphates of the formula 
##STR5## 
wherein n is 0 or 1 and R and R' denote alkyl radicals having together 11 
to 13 C atoms; 
olefinsulphonates of the formula R--CH.sub.2 --CH.dbd.CH--CH.sub.2 
--SO.sub.3.sup..crclbar. Na.sup..sym. 
wherein R denotes alkyl having 10 to 14 C atoms; fatty alcohol sulphates of 
the formula R--CH.sub.2 --O--SO.sub.3.sup..crclbar. Y.sup..sym. 
wherein R denotes alkyl having 11 to 15 C atoms and 
Y.sup..sym. denotes Na.sup..sym. or triethanolamine; 
fatty alcohol polyglycol sulphates of the formula 
EQU R--CH.sub.2 --O(C.sub.2 H.sub.4 O).sub.n --SO.sub.3.sup..crclbar. 
Na.sup..sym. 
wherein n is 2 to 7 and 
R denotes alkyl having 8 to 15 C atoms; 
sulphosuccinates of the formula 
##STR6## 
wherein n is 2 to 6 and R denotes alkyl having 11 to 13 C atoms; 
fatty alcohol polyglycol phosphates of the formula 
EQU R--CH.sub.2 --O(C.sub.2 H.sub.4 O).sub.n PO.sub.3 H.sup..crclbar. 
Na.sup..sym. 
wherein n is 2 to 6 and 
R denotes alkyl having 15 to 17 C atoms; 
alkanephosphonates of the formula 
EQU R--PO.sub.3 H.sup..crclbar. Na.sup..sym. 
wherein R denotes alkyl having 12 to 16 C atoms; 
or sodium salts of oleic acid derivatives, such as oleic acid sarcoside, 
oleic acid isothionate or oleic acid methyltauride. 
If the hydrocarbon-rich gel contains a cationic surfactant, the laminar 
mineral used must carry negative charges. Laminar silicates having 
negative charges, for example, are suitable. 
Preferred laminar silicates of this type are, in particular, the so-called 
bentonites. Either the unchanged naturally occurring products or else 
treated, in particular acid-treated, naturally occurring products can be 
used. Laminar silicates of the smectite type are particularly preferred. 
If the hydrocarbon-rich gel contains an anionic surfactant, the laminar 
mineral used must carry positive charges. Preferred laminar minerals of 
this type are, in particular, the hydrotalcites. 
The recovery of the hydrocarbon, that is to say the breakdown of the gel 
structure, is preferably carried out by adding the laminar material to the 
gel as a solid and shaking the mixture briefly. Disintegration of the gel 
then starts spontaneously and is faster, the more laminar mineral is 
added. Reasonable gel distintegration rates are achieved, depending on the 
system, when 50 to 500 mg, particularly preferably 500 to 3000 ppm, of 
laminar mineral are added per 100 g of gel. 
In particularly preferred embodiments of the process according to the 
invention, the hydrocarbon-rich gel is filtered through a layer of laminar 
mineral or pumped through a column charged with laminar mineral.