Evaporation/decomposition behavior of 1-Butyl-3-Methylimidazolium Chloride (BMImCL) investigated through effusion and thermal analysis techniques

The evaporation/decomposition behavior of the ionic liquid 1-butyl-3-methylimidazolium chloride (BMImCl) was studied with various techniques, such as thermogravimetry (TG), Knudsen effusion mass loss (KEML), and Knudsen effusion mass spectrometry (KEMS), in order to investigate the competition between the simple evaporation of the liquid as gaseous ion pairs (NIP: neutral ion pair) and the thermal decomposition releasing volatile species. TG/DSC experiments were carried out from 293 to 823 K under both He and N2 flowing atmospheres on BMImCl as well as on BMImNTf2 (NTf2: bis(trifluoromethylsulfonyl)imide). Both ionic liquids were found undergoing a single step of mass loss in the temperature range investigated. However, while the BMImNTf2 mass loss was found to occur in different temperature ranges, depending on the inert gas used, the TG curves of BMImCl under helium and nitrogen flow were practically superimposable, thus suggesting the occurrence of thermal decomposition. Furthermore, KEML experiments on BMImCl (in the range between 398 and 481 K) indicated a clear dependence of the unit area mass loss rate on the effusion hole diameter, an effect not observed for the ILs with NTf2 anion. Finally, KEMS measurements in the 416–474 K range allowed us to identify the most abundant species in the vapor phase, which resulted in methyl chloride, butylimidazole, butyl chloride, and methylimidazole, which most probably formed from the decomposition of the liquid

Synthesis and characterization of a Mg–Ni-RE alloy for hydrogen storage

The synthesis and characterization of a Mg–Ni alloy having La and Ce as catalysts, have been performed. The alloy behavior was studied at given fixed temperature and pressure during hydrogen absorption/desorption tests. The La and Ce addition was carried out starting from a commercial alloy, named “Firesteel”. The alloy synthesized has the following formula Mg68Ni26M5X, where X represents Si and Fe impurities and M stands for the mixture of rare earths metals. The alloy has been prepared by a melting process in an induction furnace equipped with a centrifugal casting system and then grinded, by both hydraulic press and ball milling. The alloy has been characterized by SEM, BET, XRD, DSC-TGA analysis and by a mass flow measurement apparatus. The experiments on alloy sample showed that, after activation, hydrogenation occurs at 300 °C in three stages at three different pressures: 3, 4 and 7 atm, involving respectively 0.15 wt%, 0.4 wt% and 2.2 wt% of hydrogen absorbed. Reversible hydride dehydrogenation, inside the mass flow measurement apparatus, requires a working temperature of 350 °C to obtain, with remarkable reaction rate, about 2.7%, hydrogen desorption

Catalytic pyrolysis of a residual plastic waste using zeolites produced by coal fly ash

The plastic film residue (PFR) of a plastic waste recycling process was selected as pyrolysis feed. Both thermal and catalytic pyrolysis experiments were performed and coal fly ash (CFA) and X zeolites synthesized from CFA (X/CFA) were used as pyrolysis catalysts. The main goal is to study the effect of low-cost catalysts on yields and quality of pyrolysis oils. NaX/CFA, obtained using the fusion/hydrothermal method, underwent ion exchange followed by calcination in order to produce HX/CFA. Firstly, thermogravimetry and differential scanning calorimetry (TG and DSC, respectively) analyses evaluated the effect of catalysts on the PFR degradation temperature and the process energy demand. Subsequently, pyrolysis was carried out in a bench scale reactor adopting the liquid-phase contact mode. HX/CFA and NaX/CFA reduced the degradation temperature of PFR from 753 to 680 and 744 K, respectively, while the degradation energy from 2.27 to 1.47 and 2.07 MJkg−1, respectively. Pyrolysis runs showed that the highest oil yield (44 wt %) was obtained by HX/CFA, while the main products obtained by thermal pyrolysis were wax and tar. Furthermore, up to 70% of HX/CFA oil was composed by gasoline range hydrocarbons. Finally, the produced gases showed a combustion energy up to 8 times higher than the pyrolysis energy needs