Combustion of methanol

M. Haruta, A. Ueda, S. Tsubota, and R.M.T. Sanchez, Low-temperature catalytic combustion of methanol and its decomposed derivative over supported gold catalysts, Catalysis Today 29, 443-447 (1996). 

C06-0071. An electric heater adds 19.75 kJ of heat to a constant-volume calorimeter. The temperature of the calorimeter increases by 4.22 °C. When 1.75 g of methanol is burned in the same calorimeter, the temperature increases by 8.47 °C. Calculate the molar energy of combustion of methanol. 

In such a device, the electrons liberated at the anode by the oxidation of methanol circulate in the external electrical circuit, producing electrical energy, and reach the cathode, where they reduce the oxidant, usually oxygen from air. The overall reaction thus corresponds to the catalytic combustion of methanol with oxygen, i.e.,... 

Explosive behaviour on combustion of methanol-air mixtures at 1.8 bar and 120°C was studied, with or without addition of oxygen and water. 

Buttner et al. (1991) studied the sonolytic effects in water-methanol mixtures under argon and oxygen conditions. Formaldehyde and peroxide have been identified as the main products. In addition, products similar to the ones formed during the pyrolysis or combustion of methanol have been observed with relative yields changing with the composition of the mixture (see Table 11.4). 

Incomplete combustion of methanol can be described by the following overall processes ... 

DMFC transforms directly the Gibbs energy of combustion of methanol into electricity, without a fuel processor (Figure 9.7). This greatly simplifies the system reducing its volume and cost. Recent development of DMFC is due to the use of proton-exchange membrane as electrolyte, instead of liquid acid electrolyte, as previously done [13]. 

Example Balance the chemical equation describing the combustion of methanol in oxygen to produce only carbon dioxide and water. 

About 1% Au/a-Fe203 is active for the combustion of methanol and its decomposition products (methanoic acid and methanal) at temperatures below 373 K, at a space velocity of 2000 h-1. Comparison of T50 values for Au/Fe2C>3 and conventional combustion catalysts Pd/Al2C>3 and Pt/A Os gave the order of activity 87... 

The alcohol lamps that are used in some science labs are often fuelled with methanol, CH3OH. Write the balanced chemical equation for the complete combustion of methanol. 

Methanol flows at the rate of 1000 kmol/h (22051b mol)into the reactor, shown in Figure 3.4.1, where methanol is oxidized catalytically to formaldehyde under non-adiabatic conditions. The reactants enter the reactor at 500 °C (932 °F), and the products exit at 600 °C (1110 °F). The methanol in stream 1 and air in stream 2 are both at 500 °C, and the methanol conversion is 80 %. To minimize possible combustion of methanol and formaldehyde, we set the molar flow rate of oxygen at 80% of the stoichiometric quantity. The reaction is... 

The combustion of methanol produces carbon dioxide and water (eqn. 2) ... 

Copper-based catalysts also display good performance in combined reforming. In a recent contribution using a Cu-ZnO catalyst, Agrell et a/.159 reported that at differential 02 conversions, water is produced by combustion of methanol. When oxygen conversion was complete, water production... 

At 298 K. the enthalpy change on combustion of methanol is — 727 kJ mo "l, that of hydrogen is - 286kimoI 1, and that of graphite 394kJmor1. Calculate the standard enthalpy of formation of methanol. 

A quantity of 1.922 g of methanol (CH3OH) was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose by 4.20°C. If the quantity of water surrounding the calorimeter was exactly 2000 g and the heat capacity of the calorimeter was 2.02 kJ/°C, calculate the molar heat of combustion of methanol. 

During these two main conversions, several side reactions of complete combustion of methanol and formaldehyde take place and reduce the overall yield of the operation. 

The production of energy alcohol on the basis of biomass plus C02-free primary energy features a C02-neutral system since the CO2 release upon combustion of methanol has been formerly extracted from the atmosphere for the biomass production. 

Figure 3>8 Racing cars are fueled by methanol. What would be the equation for the combustion of methanol ...

Figure 3.8 points out that methanol is used as a fuel in rac- 3.76 ing cars. Write a balanced equation for the combustion of methanol. 

Determine the value of the heat of combustion of methanol by using the bond energies in Table 12.1. Compare it to that of methane. 

Formaldehyde (HGHO), the simplest aldehyde, is obtained by oxidation of methanol. It is a gas at room temperature but is often used as a 40% aqueous solution called formalin. Although formaldehyde is an important starting material for polymers, it presents a number of health hazards because of its toxicity and carcinogenicity. Formaldehyde is also an air pollutant, being produced in trace amounts in the incomplete combustion of fossil fuels. One of the concerns about methanol as a fuel (Section 12.5) is the potential for increased levels of formaldehyde in urban areas because of the production of formaldehyde from incomplete combustion of methanol. 

The combustion of methanol proceeds according to the following reaction equation ... 

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