Methanol can be produced from resources such as coal, natural gas, oil shell, and farm waste, which are abundant worldwide. But methanol from natural gas is unlikely to provide a large greenhouse benefit, not more than a 10% reduction in emissions with quite optimistic assump­tions. It is not considered as a main raw material to produce methanol. For countries having vast reserves of coal but small oil deposits, methanol from coal can provide an indigenous substitute to oil. But this method has an adverse effect on greenhouse gases and is very expen­sive, requiring capital investments that can increase the price by 50%.

In India, there is an abundant production of sugarcane. The govern­ment can divert this feedstock to produce methanol. The production of methanol by using water and methane is shown in Fig. 7.9, and by using methane and a catalyst in Fig. 7.10.

Producing methanol from methane with the technology available today generally involves a two-step process. Methane is fuel reacted with water and heat to form carbon monoxide and hydrogen—together called synthesis gas. Synthesis gas is then catalytically converted to methanol. The second reaction unleashes a lot of heat, which must be removed from the reactor to preserve the activity of the temperature- sensitive catalyst. Efforts to improve methanol synthesis technology

Figure 7.9 Conversion of methane o ethanol.

focus on sustaining the catalyst life and increasing reactor productiv­ity. As a novel alternative to the two-step method, a chemical catalysis that mimics biological conversion of methane by enzymes is being devel­oped. The iron-based catalyst captures a methane molecule, adds oxygen to it, and ejects it as a molecule of methanol. If this type of conversion could be performed on a commercial scale, it would eliminate the need to first reform methane into a synthesis gas, which is a costly, energy­intensive step. Conversion of coal to methanol is simpler and cheaper as compared to its liquefactions to gasoline.

Advantages of methanol.

1. 1% methanol in petrol is used to prevent freezing of fuel in winter.

2. Tertiary-butyl alcohol is used as an octane improving agent.

3. Because of the excellent antiknock characteristics of the fuel, it is very suitable for SI engines.

4. Isopropyl alcohol is used as an anti-icing agent in carburetos.

5. Addition of methanol causes a methanol-gasoline blend to evaporate at a much faster rate than pure gasoline below its boiling point (bp).

6. Due to an increase in emission levels of conventional fuels, the per­centage of O3 in the atmosphere is increasing. This increase in the O3 in the atmosphere might cause biomedical and structural changes in the lungs which might cause chronic diseases. O3 content of even between 0.14 and 0.16 ppm temporarily affects lung function if the person is exposed to it for 1-2 h. An annual crop yield is also reduced if exposed to O3; some trees suffer injury to needles or leaves,

□ Gasoline Methano

(Indolene) (M85)

and lower productivity or even die. High content of O3 has disturbed the natural ecological balance of species in national forests in California. The effects of methanol on O3 emission as compared with petrol is shown in Fig. 7.11.