TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Substrate: The substrate (E) is extended polycyclic aromatic hydrocarbon, extended pi-conjugated substrate with nitrogen heteroatom, extended pi-conjugated substrate with heteroatom other than nitrogen, pi-conjugated organic polymer and oligomer, ionic pi-conjugated substrate, pi-conjugated monocyclic substrate with multiple nitrogen heteroatoms, pi-conjugated substrate with triple bonded group(s) and/or pitch. The extended pi-conjugated substrate with nitrogen heteroatom is phenanthroline, quinoline, N-methylindole, 1,2-dimethylindole, 1-ethyl-2-methylindole, carbazole, N-methylcarbazole, N-ethylcarbazole, N-n-propylcarbazole, N-iso-propylcarbazole, acridine, indolo(2,3-b)carbazole, indolo(3,2-a)carbazole 1,4,5,8,9,12-hexaazatriphenylene, pyrazine(2,3-b)pyrazine, N,N',N-trimethyl-6,11-dihydro-5H-diindolo(2,3-a:2',3'-c)carbazole, 1,7-dihydrobenzo(1,2-b:5,4-b')dipyrrole and/or 4H-benzo(def)carbazole. The extended pi-conjugated substrate with heteroatom other than nitrogen is dibenzothiaphene, phosphindole, P-methoxyphosphindole, P-methylphosphindole, dimethylsilaindene, boraindole, borafluorene and/or methylboraindole. The ionic pi-conjugated substrate is N-lithiocarbazole, N-lithioindole, N-lithiodiphenylamine, N-sodiumcarbazole, N-potassiumcarbazole and/or tetramethylamonium salt of carbazole. The pi-conjugated monocyclic substrate with multiple nitrogen heteroatom is pyrazine and/or N-methylimidazole. The pi-conjugated substrate with triple bonded group(s) is terephthalonitrile (1,4-dinitrilobenzene), benzonitrile and/or 1,3,5-trinitrilobenzene. The substrate (P) is mixture of two different partially hydrogenated extended pi-conjugated substrates, preferably eutectic mixture. The pi-conjugated substrate is small ring aromatic carboxylic ring or fused ring aromatic carboxylic ring having three fused carboxylic rings, heterocyclic ring analog of small ring aromatic carboxylic ring or fused ring aromatic carboxylic ring having three fused aromatic rings, phenyl-substituted silane, aryl-substituted oligomer or low molecular weight polymer of ethylene, polymer or oligomer of aryl-and vinyl-substituted siloxane, and/or low molecular weight polymer of phenylene. The small ring aromatic carboxylic ring or fused ring aromatic carboxylic ring having three fused aromatic carboxylic ring is chosen from benzene, toluene, naphthalene and/or anthracene. The polymer or oligomer of aryl-substituted siloxane is chosen from -phenyl, -tolyl, -naphthyl and/or -anthracyl. The extended pi-conjugated substrate comprises coronene, pyrene, carbazole or mixture of conformer of partially hydrogenated substrate.Preferred Pitch: The pitch or pitch fraction is natural pitch, synthetic pitch, and/or synthetic pitch containing molecules with nitrogen heteroatom, preferably natural pitch.Preferred Hydrocarbon: The extended polycyclic aromatic hydrocarbon is pyrene, perylene, coronene, ovalene, picene, rubicene, fluorene, indene, acenanaphthylene and/or pyranthrone. The polycyclic aromatic hydrocarbon comprises ring substituent chosen from alkyl, alkoxy, ether and polyether.Preferred Mixture: The eutectic mixture comprises mixture of extended pi-conjugated substrate with nitrogen heteroatom and/or extended pi-conjugated substrate with heteroatom other than nitrogen, preferably N-methylcarbazole, N-ethylcarbazole, N-propylcarbazole and/or N-isopropylcarbazole, or 1-ethyl-2-methylindole and 1,2-dimethylindole. The eutectic mixture is in liquid state at -10degreesC. Preferred Process: A single vessel or pair of vessels is used for contacting hydrogen with substrate (E), and performing catalytic dehydrogenation of substrate (P). The hydrogenation catalyst is also used as dehydrogenation catalyst. The substrate (E) is contacted with hydrogen using a vessel (1) and catalytic dehydrogenation of substrate (P) is performed in a vessel (2). The hydrogenation catalyst is removed from substrate (P), and then catalytic dehydrogenation of substrate (P) is performed. Hydrogen gas is contacted with solid extended pi-conjugates substrate in the presence of predetermined amount of hydrogenation catalyst under hydrogenation condition at hydrogen partial pressure of more than 6.7 bar and at 50-300degreesC to obtain partially hydrogenated extended pi-conjugated substrate.Preferred Properties: The substrates (E,P) exist in liquid state. The substrate (P) has melting point of less than 100degreesC, preferably -10degreesC, freezing point of less than 200degreesC, preferably less than -10degreesC, and boiling point of more than 200degreesC. The substrates (E,P) are in liquid or solid state under dehydrogenation condition. The substrate (E) does not sublime during dehydrogenation. The extended pi-conjugated substrate has freezing point of more than 200degreesC and less than 200degreesC before and after contacting with hydrogen, respectively. The liquids (1,2) have boiling point more than dehydrogenation temperature. The modulus of standard enthalpy change of hydrogenation of substrate (E) is less than 15 kcal/mol H2, and is determined experimentally or by ab initio density functional theory method.Preferred Composition: The amount of hydrogen released from substrate (P) is 1 wt.% or more with respect to weight of substrate (P), preferably 7 wt.% or more.Preferred Condition: The catalytic dehydrogenation of substrate (P) is preferably performed at less than 250degreesC, and at hydrogen partial pressure of more than 1 bar.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The pi-conjugated organic polymer or oligomer is polypyrrole, polyindole, poly(methylcarbazole), polyaniline and/or poly(9-vinylcarbazole).    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The hydrogenation catalyst and dehydrogenation catalyst comprise metal chosen from IV-VI and VIII-X group of periodic table according to International Union of Pure and Applied Chemistry, preferably titanium, zirconium, cobalt, niobium, tantalum, iron, molybdenum, tungsten, ruthenium, rhodium, iridium, nickel, palladium and/or platinum. The dehydrogenation catalyst comprises acidic support chosen from silica-alumina, (gamma)-alumina, zeolite in the proton-exchanged form, sulfonated zirconia, solid perfluorinated polymeric sulfonic acid, aluminum trifluoride, aluminum chlorofluoride, zinc chloride, aluminum chloride, tin chloride, copper trifluoromethane sulfonate, scandium trichloride, hexafluoroacetylacetonate of complexes of Lanthanide series of element according to the Period Table according to the International Union of Pure and Applied Chemistry.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Apparatus: The conduits (1,2) are situated in a housing and orifice (1) is situated adjacent to orifice (2). The conduit (1) is fitted to compartment (1) for receiving liquid (1), with unit for engaging, locking and sealing. The conduit (2) is fitted to compartment (2) for retrieving liquid (2), with unit for engaging, locking and sealing. The retrieving orifice resides the thin dispensing orifice, and vice versa. The compartments (1,2) are separated by an expandable bladder, impermeable membrane or semi-permeable membrane.Preferred Process: The liquid (2) is transferred from conduit into a receiving tank. The liquid (1) is transferred before transferring liquid (2). EXAMPLE - Sample of pyrene (in g) (0.2) and rhodium on carbon catalyst (0.1) were ground until a uniform color mixture was formed. The mixture was then placed in 50 cc high-pressure reactor equipped with a customized grinding apparatus having elongated stirrer shaft with arc-shaped paddle. Mechanical agitation of sample mixture was carried out by adding 5-8 stainless steel ball bearing of varying size. The stirrer motor was programmed such that rotational direction of the stirrer would alternate between clockwise and counterclockwise directions during the course of the reaction in order to ensure that the sample mixture would contact the grinding balls. Once the sample mixture and grinding balls were loaded into the reactor, the system was pressurized with helium to 1000 psia (69 bar) and vented. Pressurization and venting with helium was repeated three times. The reactor system was then twice pressurized to 1000 psia hydrogen and vented. After completing purging, sample mixture was hydrogenated by grinding at 95degreesC and 1000 psia for 1.5 hours. After completing reaction, the reactor was then quickly cooled to room temperature and vented. Half of the sample mixture was removed from the reactor (h-pyrene), and the remaining material was left in the reactor for dehydrogenation. The material to be dehydrogenated was purged and ground at 95degreesC and 15 psia (1 bar) hydrogen for three hours, before reactor was cooled to room temperature. The sample was then removed for analysis (dh-pyrene). Both of the hydrogenated pyrene (h-pyrene) and dehydrogenated h-pyrene (dh-pyrene) samples were separated from the catalyst by extraction with chloroform and filtering insoluble catalyst. The chloroform was then removed under vacuum to obtain the pure products. Hydrogenated and dehydrogenated h-pyrene were subjected to Gas chromatography-Mass spectroscopy (GC-MS) and proton nuclear magnetic resonance (NMR) spectroscopy analyses, and indicated that 99% or more of pyrene raw material was converted to mixture of hydrogenated products, gravimetric storage capacity of hydrogen was 2.3 wt.% with respect to total sample weight (pyrene+catalyst). Upon dehydrogenation, GC-MS indicated that approximately 25% of the hydrogenated material is converted back to pyrene.