Hydrogen Production From Methanol-prashant Mishra

Hydrogen production from methanol 1. Introduction There is a growing necessity to find alternative ways to produce energy with lower emissions of pollutants and higher efficiencies compared to internal combustion. One such option is the use of proton exchange membrane (PEM) fuel cell system. PEM fuel cells convert hydrogen gas into useful electric power with an efficiency that is not limited by thermodynamics and the only by product is water. Due to current infrastructure, storage technology and safety concerns, hydrogen gas cannot be stored on-board in adequate amounts for mobile applications. On demand reforming of liquid hydrocarbons to produce hydrogen is seen as an attractive means of providing the necessary hydrogen to the fuel cell. With the exception of formic acid, Methanol is the easiest hydrocarbon to reform. On board methanol reforming has a couple of advantages over other potential fuels: unlike gasoline or diesel fuel, Liquid methanol can be easily readily produced by biomass, it is easy to transport and store. It has high hydrogen density.the basic way hydrogen generation from methanol is decomposition of pure metnanol. It is endothermic reaction with 90.7 kj/mol heat of reaction. It produces carbon mono oxide which is harmful for health and poison for fuel cell. So some downstream plants eliminate it before releasing product gas for fuel gas. It can also produce come bi-product like di-methyl ether and methane.

TECHNOLOGY: A mixture of water and methanol with a molar concentration ratio (water: methanol) of 1.3 - 1.5 is pressurized to approximately 20 bar, vaporized and heated to a temperature of 250 - 280 °C. The hydrogen that is created is separated through the use of a hydrogen-permeable membrane made of a palladium and silver alloy. There are two basic methods of conducting this process. •

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The water-methanol mixture is introduced into a tube-shaped reactor where it makes contact with the catalyst. The hydrogen is then separated from the other reactants and products in a later chamber. The reformed material passes the PdAg membrane and most of the hydrogen passes through. The other variety features an integrated reaction chamber and separation membrane. In such a design the walls of the reaction chamber are made from a PdAg-coated ceramic cylinder and the hydrogen is thereby separated directly out of the reaction chamber.

With either design, not all of the hydrogen is removed from the product of the reaction, so the remaining gas mixture still contains a significant amount of hydrogen. As such, this resulting mixture is often mixed with air and burned. The heat energy produced by burning this mixture can be used for heating purposes. Advantages and disadvantages Methanol reformers are being considered as a component of a hydrogen fuel cell-powered vehicle. A prototype car, the NECAR 5, was introduced by Daimler-Chrysler in the year 2000. The primary advantage of a vehicle with a reformer is that it does not need a pressurized gas tank to store hydrogen fuel; instead methanol is stored as a liquid. The logistic implications of this are great; pressurized hydrogen is difficult to store and produce. Also, this could help ease the public's concern over the danger of

hydrogen and thereby make fuel cell powered vehicles more attractive. However, methanol, like gasoline, is toxic and (of course) flammable. The cost of the PdAg membrane and its susceptibility to damage by temperature changes provide obstacles to adoption. Another problem is that although hydrogen power produces energy without CO2, a methanol reformer creates the gas as a byproduct. The high level of greenhouse gases in our atmosphere significantly contributes to global warming. Methanol (prepared from natural gas) that is used in an efficient fuel cell, however, releases less CO2 in the atmosphere than gasoline, in a net analysis.

EFFECT OF CATLYTIC FORMATION AND REACTION CONDITION ON PRODUCTION OF HYDROGEN FROM METHANOL THROUGH DECOMPOSITON OVER Pt AND Pd CATALYSTS – CATALYST PREPARATIONSteps to prepare Pt/Al2O3 and Pd/Al2O31).Method, a known amount of aluminum isopropoxide (AIP), 98% was hydrolyzed in water at 85 deg C. 2). Then a small amount of nitric acid was added to obtain a clear sol. 3). After that, the necessary amount of either H2PtCl6 or Pd(NO3)2 precursor was added to obtain the desired metal loading (from 1 to 10 wt %) in the final catalyst formulation. 4). Pt or Pd precursor solution was added last.

5). After evaporating the excess solvent. Gel form is obtained and then dried at 110 _C for 24 h to remove water and solvent. Effects of Pt loading-effect of Pt loading on decomposition of metnanol and composition of product steam. 1).three loading of Pt were investigated-2%, 5%, 9% The results of the activity tests for different Pt loading catalysts on sol–gel alumina are displayed in Fig.

2). Decomposition activity was increased when the Pt loading was increased from 2% to 9%. The complete conversion temperature dropped from 405 to 390 deg C. Further increasing the loading had no effect on the activity. 3). The 5% and 9% Pt catalysts exhibited essentially 100% hydrogen selectivity for all conversions (hydrogen selectivity is defined as the fraction of hydrogen in methanol that ends up as molecular hydrogen). 4). The 2% Pt catalyst started forming methane at 360 deg C and the selectivity for hydrogen dropped

to 92% at the maximum conversion temperature of 405 deg C. 5). Since production of maximum amount of hydrogen is the goal, the methanation reaction is From the methanation (2) reaction, H2O is formed. Water can participate in the water gas shift reaction (WGS)

6). The production rates of hydrogen are 289 mmol/s kg for the 9% Pt catalyst, for the 2% Pt it is 273 mmol/s kg catalyst because of the lower selectivity.

Hydrogen Production of Methanol Reformation Using Cu/ZnO/Al2O3 Catalyst:

The catalytic performance of methanol reformation using Cu/ZnO/Al2O3 was investigated at low temperature. The operation conditions, such as composition of Cu, Zn, and Al, temperature, molar ratio of H2O/CH3OH, weight hourly space velocity, catalyst weight, and kind and flow rate of carrier gas (helium and air), were evaluated to obtain the optimum

reaction condition. The catalysts were prepared by oxalic coprecipitation, coprecipitation, and polyol method. The weight composition of Cu, Zn, and Al prepared by oxalic coprecipitation was 15:15:5 by high-throughput screening of combinatorial chemistry method, which was the best Cu/ZnO/Al2O3 catalyst. The prepared catalysts showed high activity and selectivity towards hydrogen formation. The methanol conversion, production rate, and volumetric percentage of hydrogen using this best catalyst were larger than 95%, 0.65 mol/h·g and 59%, respectively, and the CO volumetric percentage was smaller than 0.22% when the reaction temperature was 240 °C.

PRASHANT MISHRA B.TECH.(AUTOMOTIVE DESIGN ENGG.) UNIVERSITY OF PETROLEUM AND ENERGY STUDIES DEHRADUN (U.K.)