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BIOMASS AND BIOCNERCY 35 (20 1 i) 822-826 823

purify by-product glycerine before using for such purposes. The effective method of purification of glycerine is distillation. Because of higher boiling point of glycerine at atmospheric pressure (290 ~C). distillation process is needed to be carried out at Iow pressures. Vacuum distillation is difhcult and expensive. Also glycerine demand in the medicine, cosmetic areas at the world market is limited. It is therefore necessary to find means for effective and economical utilization of glycerine and to create market for vast amounts of glycerine [4].

Considering the Chemical formula of glycerine (CiH_aOj). it is possible to form 4 mol of hydrogen from 1 mol of glycerine. Therefore glycerine is a potential feedstock to produce hydrogen. Hydrogen can be obtained from glycerine via steam reforming (SR) or aqueous-phase reforming (APR) methods. External energy supply at APR becomes much lower than SR because APR is carried out at lower temperatures. Since the temperaturę employed is also suitable for water gas shift reaction, it is possible to have lower CO concentrations in one reactor. Another important advantage of APR (Eq. (1)) is the ability of producing 7 mol of hydrogen per 1 mol of glycerol, four from glycerol itself and three from water (5). The resulting hydrogen can be used as a fuel in intemal combustion engines and fuel cells, and to produce Chemicals such as ammonia, methanol, etc.

C₃H*0* + 3H₂0i + 346MJ Kmol~3C0₂,, + 7H₂ „    (1)

Earlier studies have been focused mainly on the effects of catalysts on APR of glycerol [6-11J. It has been found that Pt/ Al₂0₅ is the most suitable catalyst for APR of glycerol (6-10,12). But, not many systematic studies have been reported in the literaturę to reveal the effects of temperaturę, flow ratę and concentration of the feed stream. The ob;ective in this work was to investigate the process conditions that would give the maximum yield of H*

2.    Experimental

APR of glycerol was carried out in two different Systems. The first one was batch, the other was continuous system. Reac-tions at two systems were carried out in a medium of Pt/Al₂03 catalyst (Aldrich-232114). After reactions performed, output gas products were analyzed with gas chromatography (SRI 310C and SRI 8610C GCs).

2.1.    Batch system

Batch system included autoclave reactor and control panel (Parr Instrument-4590). 2 g of 1 wt-% Pt/Al₂Oj with the 3.2 mm particie size in the pellet form was used as the catalyst. After glycerol, water and catalyst were charged to the autoclave reactor. temperaturę was set to the desired reaction condition. Pressure was monitored to follow the conversion to hydrogen.

2.2.    Continuous system

Continuous ftxed-bed reactor system is shown in Fig. 1. Glycerol was fed to the reactor with a high pressure pump providing adjustable flow rates (Cole-Parmer/74930-05). APR

Fig. 1 - Experimental set up for APR of glycerol. (1) Argon cylinder; (2) Reactant beaker, (3) High Pressure Pump; (4) Variac; (5) Heating tape; (6) Fixed-bed reactor (7) Heat exchanger; (8) Separator; (9) Pressure regulator; P-Manometer, V-Valve.