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In the Gutzeit test, AsH 3 is generated by reduction of aqueous arsenic compounds, typically arsenites, with Zn in the presence of H 2 SO 4. The evolved gaseous AsH 3 is then exposed to AgNO 3 either as powder or as a solution. With solid AgNO 3, AsH 3 reacts to produce yellow Ag 4 AsNO 3, whereas AsH 3 reacts with a solution of AgNO 3 to give ...
If, however, hydrogen is the desired end-product, the coal gas (primarily the CO product) undergoes the water gas shift reaction where more hydrogen is produced by additional reaction with water vapor: CO + H 2 O → CO 2 + H 2. Although other technologies for coal gasification currently exist, all employ, in general, the same chemical processes.
For the production of hydrogen from coal, coal gasification is used. The process of coal gasification uses steam and oxygen to break molecular bonds in coal and form a gaseous mixture of hydrogen and carbon monoxide. [53] Carbon dioxide and pollutants may be more easily removed from gas obtained from coal gasification versus coal combustion.
One of the simplest arsenic compounds is the trihydride, the highly toxic, flammable, pyrophoric arsine (AsH 3). This compound is generally regarded as stable, since at room temperature it decomposes only slowly. At temperatures of 250–300 °C decomposition to arsenic and hydrogen is rapid. [34]
The hydrogen atoms in the arsinide anion may be substituted by organic or other groups which can then also produce ions, for example by methyl −CH 3, like in potassium methyl arsinide (K + CH 3 AsH −), [12] or by trimethylsilyl −Si(CH 3) 3. [1] The doubly bonded ligand =AsH (or AsH 2−) is called arsinidene. [11]
A typical hydrogen demand is ~80 kg [citation needed] hydrogen per ton of dry, ash-free coal. Generally, this process is similar to hydrogenation. The output is at three levels: heavy oil, middle oil, gasoline. The middle oil is hydrogenated in order to get more gasoline and the heavy oil is mixed with the coal again and the process restarts.
Steam can be added to the reaction in order to increase the generation of H 2, via the water-gas shift reaction (WGS) and/or steam methane reforming. The CLR process can produce a syngas with a H 2:CO molar ratio of 2:1 or higher, which is suitable for Fischer–Tropsch synthesis, methanol synthesis, or hydrogen production. The reduced oxygen ...
The product gas is brought to the surface through production wells drilled from the surface. [1] The predominant product gases are methane, hydrogen, carbon monoxide and carbon dioxide. Ratios vary depending upon formation pressure, depth of coal and oxidant balance. Gas output may be combusted for electricity production.