Performance of a mixed-conducting ceramic membrane reactor with high oxygen permeability for methane conversion

A mixed-conducting perovskite-type Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCFO) ceramic membrane reactor with high oxygen permeability was applied for the activation of methane. The membrane reactor has intrinsic catalytic activities for methane conversion to ethane and ethylene. C₂ selectivity up to 40–70% was achieved, albeit that conversion rate were low, typically 0.5–3.5% at 800–900°C with a 50% helium diluted methane inlet stream at a flow rate of 34 ml/min. Large amount of unreacted molecular oxygen was detected in the eluted gas and the oxygen permeation flux improved only slightly compared with that under non-reactive air/He experiments. The partial oxidation of methane to syngas in a BSCFO membrane reactor was also performed by packing LiLaNiO/γ-Al₂O₃ with 10% Ni loading as the catalyst. At the initial stage, oxygen permeation flux, methane conversion and CO selectivity were closely related with the state of the catalyst. Less than 21 h was needed for the oxygen permeation flux to reach its steady state. 98.5% CH₄ conversion, 93.0% CO selectivity and 10.45 ml/cm² min oxygen permeation flux were achieved under steady state at 850°C. Methane conversion and oxygen permeation flux increased with increasing temperature. No fracture of the membrane reactor was observed during syngas production. However, H₂-TPR investigation demonstrated that the BSCFO was unstable under reducing atmosphere, yet the material was found to have excellent phase reversibility. A membrane reactor made from BSCFO was successfully operated for the POM reaction at 875°C for more than 500 h without failure, with a stable oxygen permeation flux of about 11.5 ml/cm² min.     

Fabrication and magnetic properties of electrospun copper ferrite (CuFe2O4) nanofibers

Tetragonal copper ferrite (CuFe₂O₄) nanofibers were fabricated by electrospinning method using a solution that contained poly(vinyl pyrrolidone) (PVP) and Cu and Fe nitrates as alternative metal sources. The as-spun and calcined CuFe₂O₄/PVP composite samples were characterized by TG-DTA, X-ray diffraction, FT-IR, and SEM, respectively. After calcination of the as-spun CuFe₂O₄/PVP composite nanofibers (fiber size of 89 ± 12 nm in diameter) at 500 °C in air for 2 h, CuFe₂O₄ nanofibers of 66 ± 13 nm in diameter having well-developed tetragonal structure were successfully obtained. The crystal structure and morphology of the nanofibers were influenced by the calcination temperature. After calcination at 600 and 700 °C, the nature of nanofibers changed which was possibly due to the reorganization of the CuFe₂O₄ structure at high temperature, and a fiber structure of packed particles or crystallites was prominent. Crystallite size of the nanoparticles contained in nanofibers increases from 7.9 to 23.98 nm with increasing calcination temperature between 500 and 700 °C. Room temperature magnetization results showed a ferromagnetic behavior of the calcined CuFe₂O₄ samples, having their specific saturation magnetization (M_s) values of 17.73, 20.52, and 23.98 emu/g for the samples calcined at 500, 600, and 700 °C, respectively.     

Physico–chemical properties of CdO–Al2O3 catalysts. I – Structural characteristics

Alumina gels AN6 and AN7 were prepared by precipitation with NaOH from hydrated aluminum sulfate at pH 6 and 7, respectively. A third alumina gel AA7 was similarly prepared, but by precipitation with 30% ammonia. Pure cadmia C8 and C9 were precipitated from cadmium sulfate at pH 8 and 9 using NaOH. Five mechanically mixed gels ACM (1:0.25), ACM (1:0.5), ACM (1:1), ACM (0.5:1) and ACM (0.25:1) were prepared by thoroughly mixing the appropriate molar ratios of AN7 and C8. Also, five coprecipitated gels ACC (1:0.25), ACC (1:0.5), ACC (1:1), ACC (0.5:1) and ACC (0.25:1) were coprecipitated by dropping simultaneously the appropriate volumes of 1 M aluminum sulfate, 1 M cadmium sulfate and 3 M NaOH. Calcination products at 400, 500, 600, 800 and 1000 °C were obtained from each preparation.TG–DTA patterns of uncalcined samples were analyzed and the XRD of all 1000 °C-products and some selected samples calcined at 400–800 °C were investigated. The thermal behaviors of pure and mixed gels depend on the precipitating agent, pH of precipitation, chemical composition and method of preparation. Generally, calcination at temperatures below 800 °C gave poorly crystalline phases. Well crystalline phases are obtained at 800 and 1000 °C. For pure alumina γ-Al₂O₃ was shown as 400 °C-calcination product that transforms into the δ form around 900 °C and later to θ-Al₂O₃ as a major phase and α-Al₂O₃ as a minor phase at 1000 °C. CdO was shown by 500 °C-calcined cadmia gel that showed color changes with rise of calcination temperature. The most stable black cadmium oxide phase (Monteponite) is obtained upon calcination at 1000 °C. Thousand degree celsius- calcined mixed oxides showed θ-Al₂O₃, α-Al₂O₃, CdAl₂O₄ and monteponite which dominate depending on the chemical composition.     

Syngas Production from Lignite Coal Using K2CO3 Catalytic Steam Gasification with Controlled Heating Rate in Pyrolysis Step

Gasification uses steam increases H2 content in the syngas. Kinetics of gasification process can be improved by using K₂CO₃ catalyst. Controlled heating rate in pyrolysis step determines the pore size of charcoal that affects yield gas and H₂ and CO content in the syngas. In previous research, pyrolisis step was performed without considering heating rate in pyrolysis step. This experiment was performed by catalytic steam gasification using lignite char from pyrolysis with controlled heating rate intended to produce maximum yield of syngas with mole ratio of H₂/CO ≈ 2. Slow heating rate (3 °C/min) until 850 °C in the pyrolysis step has resulted in largest surface area of char. This study was performed by feeding Indonesian lignite char particles and K₂CO₃ catalyst into a fixed bed reactor with variation of steam/char mole ratio (2.2; 2.9; 4.0) and gasification temperature (750 °C, 825 °C, and 900 °C). Highest ratio of H₂/CO (1.682) was obtained at 750 °C and steam/char ratio 2.2. Largest gas yield obtained from this study was 0.504 mol/g of char at 900 °C and steam/char ratio 2.9. Optimum condition for syngas production was at 750 °C and steam/char mole ratio 2.2 with gas yield 0.353 mol/g of char and H₂/CO ratio 1.682.     

The effects of temperature on product yields and composition of bio-oils in hydropyrolysis of rice husk using nickel-loaded brown coal char catalyst

Hydropyrolysis of rice husk was performed using nickel-loaded Loy Yang brown coal char (Ni/LY) catalyst in a fluidized bed reactor at 500, 550, 600 and 650 °C with an aim to study the influence of catalyst and catalytic hydropyrolysis temperature on product yields and the composition of bio-oil. An inexpensive Ni/LY char was prepared by the ion-exchange method with nickel loading rate of 9 ± 1 wt.%. Nickel particles which dispersed well in Loy Yang brown coal char showed a large specific surface area of Ni/LY char of 350 m²/g. The effects of catalytic activity and hydropyrolysis temperature of rice husk using Ni/LY char were examined at the optimal condition for bio-oil yield (i.e., pyrolysis temperature 500 °C, static bed height 5 cm, and gas flow rate 2 L/min without catalyst). In the presence of catalyst, the oxygen content of bio-oil decreased by about 16% compared with that of non-catalyst. Raising the temperature from 500 to 650 °C reduced the oxygen content of bio-oil from 27.50% to 21.50%. Bio-oil yields decreased while gas yields and water content increased with increasing temperature due to more oxygen being converted into H₂O, CO₂, and CO. The decreasing of the oxygen content contributed to a remarkable increase in the heating value of bio-oil. The characteristics of bio-oil were analyzed by Karl Fischer, GC/MS, GPC, FT-IR, and CHN elemental analysis. The result indicated that the hydropyrolysis of rice husk using Ni/LY char at high temperature can be used to improved the quality of bio-oil to level suitable for a potential liquid fuel and chemical feedstock.     

Oxygen selective ceramic hollow fiber membranes

Oxygen ion conducting Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ hollow fiber membranes with o.d. 1.15 mm and i.d. 0.71 mm were fabricated using a sequence of extrusion, gelation, coating and sintering steps. The starting ceramic powder was synthesized by combined EDTA–citrate complexing followed by thermal treatment at 900 °C. The powder was then dispersed in a polymer solution, and extruded through a spinerette. After gelation, an additional thin coating of the ceramic powder was applied on the fiber, and sintering was carried out at 1190 °C to obtain the final ceramic membrane. The fibers were characterized by SEM, and tested for air separation at ambient pressure and at temperatures between 700 and 950 °C. The maximum oxygen flux measured was 5.1 mL/min/cm² at 950 °C.     

Semivolatile and volatile compounds from the pyrolysis and combustion of polyvinyl chloride

Emissions evolved from the pyrolysis and combustion of polyvinyl chloride (PVC) were studied at four different temperatures (500, 700, 850 and 1000 °C) in a horizontal laboratory tubular quartz reactor in order to analyse the influence of both temperature and reaction atmosphere on the final products from thermal and oxidative reactions. It was observed that the CO₂/CO ratio increased with temperature. Methane was the only light hydrocarbon whose yield increased with temperature up to 1000 °C. Benzene was rather stable at high temperatures, but in general, combustion at temperatures above 500 °C was enough to destroy light hydrocarbons. Semivolatile hydrocarbons were collected in XAD-2 resin and more than 160 compounds were detected. Trends on polyaromatic hydrocarbon (PAH) yields showed that most had a maximum at 850 °C in pyrolysis, but naphthalene at 700 °C. Formation of chlorinated aromatics was detected. A detailed analysis of all isomers of chlorobenzenes and chlorophenols was performed. Both of them reached higher total yields in combustion runs, the first ones having a maximum at 700 °C and the latter at 500 °C. Pyrolysis and combustion runs at 850 °C were conducted to study the formation of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs). There was more than 20-fold increase in total yields from pyrolysis to combustion, and PCDF yields represented in each case about 10 times PCDD yields.     

Effect of heating on speciation of copper in Si/Al/Ca-based environmental matrices

X-ray absorption spectroscopy is used to investigate the speciation of sorbed copper in heated fly ash. CuO and Cu(OH)₂ are determined to be the principal copper species in the Cu-sorbing fly ash heated at 500 °C for 2 h. Heating the Cu-sorbing fly ash to 900 °C or 1100 °C can result in the formation of CuSO₄, representing 41% and 32% of the total copper, respectively. Ash sintering and/or co-melting at 900 and 1100 °C occur, thereby triggering chemical reaction between CuO/Cu(OH)₂ and sulfur compounds.     

Ni–Al hydrotalcite-like material as the catalyst precursors for the dry reforming of methane at low temperature

Nickel–aluminium and magnesium–aluminium hydrotalcites were prepared by co-precipitation and subsequently submitted to calcination. The mixed oxides obtained from the thermal decomposition of the synthesized materials were characterized by XRD, H₂-TPR, N₂ sorption and elemental analysis and subsequently tested in the reaction of methane dry reforming (DRM) in the presence of excess of methane (CH₄/CO₂/Ar = 2/1/7). DMR in the presence of the nickel-containing hydrotalcite-derived material showed CH₄ and CO₂ conversions of ca. 50% at 550 °C. The high values of the H₂/CO molar ratio indicate that at 550 °C methane decomposition was strongly influencing the DRM process. The sample reduced at 900 °C showed better catalytic performance than the sample activated at 550 °C. The catalytic performance in isothermal conditions from 550 °C to 750 °C was also determined.     

Partial oxidation of ethane to syngas in an oxygen-permeable membrane reactor

A perovskite-type oxide of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCFO) with mixed electronic and oxygen ionic conductivity at high temperatures was used as an oxygen-permeable membrane. A tubular membrane of BSCFO made by extrusion method has been used in the membrane reactor to exclusively transport oxygen for the partial oxidation of ethane (POE) to syngas with catalyst of LiLaNiO/γ-Al₂O₃ at temperatures of 800–900 °C. After only 30 min POE reaction in the membrane reactor, the oxygen permeation flux reached at 8.2 ml cm⁻² min⁻¹. After that, the oxygen permeation flux increased slowly and it took 12 h to reach at 11.0 ml cm⁻² min⁻¹. SEM and EDS analysis showed that Sr and Ba segregations occurred on the used membrane surface exposed to air while Co slightly enriched on the membrane surface exposed to ethane. The oxygen permeation flux increased with increasing of concentration of C₂H₆, which was attributed to increasing of the driving force resulting from the more reducing conditions produced with an increase of concentration of C₂H₆ in the feed gas. The tubular membrane reactor was successfully operated for POE reaction at 875 °C for more than 100 h without failure, with ethane conversion of ∼100%, CO selectivity of >91% and oxygen permeation fluxes of 10–11 ml cm⁻² min⁻¹.     

Syngas production from pyrolysis–catalytic steam reforming of waste biomass in a continuous screw kiln reactor

A two-stage continuous screw-kiln reactor was investigated for the production of synthesis gas (syngas) from the pyrolysis of biomass in the form of waste wood and subsequent catalytic steam reforming of the pyrolysis oils and gases. Four nickel based catalysts; NiO/Al₂O₃, NiO/CeO₂/Al₂O₃, NiO/SiO₂ (prepared by an incipient wetness method) and another NiO/SiO₂ (prepared by a sol–gel method), were synthesized and used in the catalytic steam reforming process. Pyrolysis of the biomass at a rapid heating rate of approximately 40 °C/s, was carried out at a pyrolysis temperature of 500 °C and the second stage reforming of the evolved pyrolysis gases was carried out with a catalytic bed kept at a temperature of 760 °C. Gases were analysed using gas chromatography while the fresh and reacted catalyst was analysed by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy with energy dispersive X-ray and X-ray photoelectron spectroscopy. The reactor design was shown to be effective for the pyrolysis and catalytic steam reforming of biomass with a maximum syngas yield of 54.0 wt.% produced when the sol–gel prepared NiO/SiO₂ catalyst was used, which had the highest surface area of 765 m² g⁻¹. The maximum H₂ production of 44.4 vol.% was obtained when the NiO/Al₂O₃ catalyst was used.     

Synthesis and characterization of high surface area TiO2/SiO2 mesostructured nanocomposite

Recently titania synthesis was reported using various structuration procedures, leading to the production of solid presenting high surface area but exhibiting moderate thermal stability. The study presents the synthesis of TiO₂/SiO₂ nanocomposites, a solid that can advantageously replace bulk titania samples as catalyst support. The silica host support used for the synthesis of the nanocomposite is a SBA-15 type silica, having a well-defined 2D hexagonal pore structure and a large pore size. The control of the impregnation media is important to obtain dispersed titania crystals into the porosity, the best results have been obtained using an impregnation in an excess of solvent. After calcination at low temperature (400 °C), nanocomposites having titania nanodomains (～2–3 nm) located inside the pores and no external aggregates visible are obtained. This nanocomposite exhibits high specific surface area (close to that of the silica host support, even with a titania loading of 55 wt.%) and a narrow pore size distribution. Surprisingly, the increase in calcination temperature up to 800 °C does not allow to detect the anatase to rutile transition. Even at 800 °C, the hexagonal mesoporous structure of the silica support is maintained, and the anatase crystal domain size is evaluated at ～10 nm, a size close to that of the silica host support porosity (8.4 nm). Comparison of their physical properties with the results presented in literature for bulk samples evidenced that these TiO₂/SiO₂ solids are promising in term of thermal stability.     

Pyrolysis of textile wastes: I. Kinetics and yields

Thermal behavior of textile waste was studied by thermogravimetry at different heating rates and also by semi-batch pyrolysis. It was shown that the onset temperature of mass loss is within 104–156 °C and the final reaction temperature is within 423–500 °C. The average mass loss is 89.5%. There are three DTG peaks located at the temperature ranges of 135–309, 276–394 and 374–500 °C, respectively. The first two might be associated with either with decomposition of the hemicellulose and cellulose or with different processes of cellulose decomposition. The third peak is possibly associated to a synthetic polymer. At a temperature of 460 °C, the expected amount of volatiles of this waste is within 85–89%. The kinetic parameters of the individual degradation processes were determined by using a parallel model. Their dependence on the heating rate was also established. The pyrolysis rate is considered as the sum of the three reaction rates. The pyrolysis in a batch reactor at 700 °C and nitrogen flow of 60 ml/min produces 72 wt.% of oil, 13.5 wt.% of gas and 12.5 wt.% of char. The kinetic parameters of the first peak do not vary with heating rate, while those of the second and the third peak increase and decrease, respectively, with an increasing heating rate, proving the existence of complex reaction mechanisms for both cases.     

Structural changes in coal chars after pressurized pyrolysis

The aim of this work was to evaluate the effect of pressure on the structural properties and subsequent reactivity of coal chars. Pyrolysis reactions were carried out in a fixed bed reactor by varying the pressure up to 2.0 MPa. Two coal samples with a substantial difference in the swelling index were used for the analysis. Pyrolysis experiments were carried out at 800 °C for 30 min after heating the sample at a constant rate of 20 °C/min and some samples were pyrolyzed at 900 °C and 0.1 MPa for comparison. Structural analysis of the coal chars was performed using Raman microscopy; this characterization was complemented by scanning electron microscopy analysis, gas adsorption and reactivity towards molecular oxygen in a thermogravimetric equipment. Characteristic Raman bands of coal chars exhibited significant changes from 0.1 to 0.5 MPa, after this pressure no significant changes were observed with pressure increments. The pyrolysis pressure showed to have an influence in the ordering of the carbonaceous structures through the deconvoluted Raman spectra.     

Gold & silver nanoparticles supported on manganese oxide: Synthesis,characterization and catalytic studies for selective oxidation of benzyl alcohol

Nano-gold and silver particles supported on manganese oxide were synthesized by the co-precipitation method. The catalytic properties of these materials were investigated for the oxidation of benzyl alcohol using molecular oxygen as a source of oxygen. The catalyst was calcined at 300, 400 and 500 °C. They were characterized by electron microscopy, powder X-ray diffraction (XRD) and surface area. It was observed that the calcination temperature affects the size of the nanoparticle, which plays a significant role in the catalytic process. The catalyst calcined at 400 °C, gave a 100% conversion and >99% selectivity, whereas catalysts calcined at 300 and 500 °C gave a conversion of 69.51% and 19.90% respectively, although the selectivity remains >99%.     

Influence of Calcination on the Properties of Nickel Oxide-Samarium Doped Ceria Carbonate (NiO-SDCC) Composite Anodes

Apart from its composition, the starting powder properties such as particle size potentially affect the triple phase boundary and the electrochemical performance. Calcination process has been identified as one of the factors that influence the particle size of the composite anode powders. This study investigates the correlation between calcination temperature and properties (i.e., chemical, physical, and thermal) of NiO–samarium-doped ceria carbonate (SDCC) composite anodes. NiO–SDCC composite anode powder was prepared with NiO and SDCC through high-energy ball milling. The resultant composite powder was subjected to calcination at various temperatures ranging from 600 °C to 800 °C. Characterizations of the composite anode were performed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), dilatometry, and porosity measurements. The composite anodes exhibited good chemical compatibility during XRD after calcination and sintering. The FTIR result verified the existence of carbonates in all the composite anodes. The increment in calcination temperature from 600 °C to 800 °C resulted in the growth of nanoscale particles, as evidenced by the FESEM micrographs and crystallite size. Nonetheless, the porosity obtained remained within the acceptable range for a good anodic reaction (20% to 40%). The TGA results showed gradual mass loss in the range of 400 °C to 600 °C (within the low-temperature solid oxide fuel cell region). The composite anodes calcined at 600 °C and 700 °C revealed a good thermal expansion coefficient that matches that of the SDCC electrolyte.     

Utilization of Low-grade Iron Ore in Ammonia Decomposition

Due to its cleanliness, fast energy cycle, and convenience of energy conversion, hydrogen has been regarded as the new energy source. Conventional process to produce hydrogen yield large amount of CO as byproduct. Moreover, the hydrogen storage and transportation have become the drawbacks in hydrogen economy. Thus, there has been increased interest in the hydrogen transportation medium as alternatives from the conventional process to produce and transport hydrogen. Ammonia has drawn worldwide attention as the most reliable hydrogen transportation medium. Through the decomposition of ammonia, hydrogen and nitrogen gas were produces as the byproduct without any CO or CO₂ emission. In this experiment, the ore were introduced as the medium for ammonia decomposition. The ore were put into quartz tube reactor and were dehydrated at 400 °C for 1 hour, then hydrogen reduced for 2 hours before and undergone ammonia decomposition at 500-700 °C for 3 hours. The effects of temperature to the % conversion of ammonia decomposition were also studied. Ammonia decomposition at higher temperature gives higher conversion. As seen in the results, the NH₃ conversion decreased with increasing time and the value after 3 hours of reaction increased in the sequence of 500 °C<600 °C< 700 °C. During ammonia decomposition, nitriding of iron occurred. The relation between temperature and the nitriding potential, K_N is also investigated. The purpose of this study is to investigate the utilization of low-grade ore as medium for ammonia decomposition to produce hydrogen.     

Infiltrated Sr2Fe1.5Mo0.5O6/La0.9Sr0.1Ga0.8Mg0.2O3 electrodes towards high performance symmetrical solid oxide fuel cells fabricated by an ultra-fast and time-saving procedure

Herein, the Sr₂Fe_1.5Mo_0.5O₆ (SFM) precursor solution is infiltrated into a tri-layered “porous La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ (LSGM)/dense LSGM/porous LSGM” skeleton to form both SFM/LSGM symmetrical fuel cells and functional fuel cells by adopting an ultra-fast and time-saving procedure. The heating/cooling rate when fabricating is fixed at 200 °C/min. Thanks to the unique cell structure with high thermal shock resistance and matched thermal expansion coefficients (TEC) between SFM and LSGM, no SFM/LSGM interfacial detachment is detected. The polarization resistances (Rp) of SFM/LSGM composite cathode and anode at 650 °C are 0.27 Ω·cm² and 0.235 Ω·cm², respectively. These values are even smaller than those of the cells fabricated with traditional method. From scanning electron microscope (SEM), a more homogenous distribution of SFM is identified in the ultra-fast fabricated SFM/LSGM composite, therefore leading to the enhanced performance. This study also strengthens the evidence that SFM can be used as high performance symmetrical electrode material both running in H₂ and CH₄. When using H₂ as fuel, the maximum power density of “SFM-LSGM/LSGM/LSGM-SFM” functional fuel cell at 700 °C is 880 mW cm^− 2. By using CH₄ as fuel, the maximum power densities at 850 and 900 °C are 146 and 306 mW cm^− 2, respectively.     

Photoluminescence of La/Ti mixed oxides prepared using sol–gel process and their pCBA photodecomposition

La/Ti mixed oxides with weight ratios of 1:9, 2:8, 3:7, and 4:6 were prepared by sol–gel method. The photocatalytic activity of La/Ti oxides was evaluated based on the pCBA photodecomposition. The catalyst samples were characterized by XRD, TEM, DRS, BET, and photoluminescence (PL) spectra. Particles of the La/Ti-mixed oxides showed the diameter of about 7 nm. We found that 30% doping of lanthanum ions on the TiO₂ powders induced the highest pCBA (4-chlorobenzonic acid) photodecomposition in these experimental conditions. The order of its photoactivity was as following: 30 > 20 > 0 > 10 > 40 wt%, which was the same for PL tendency. Also, PL spectra intensity increased with calcination temperature from 500 to 600 °C, then decreased at 700 °C. Phtotcatalytic activity followed the trend of the PL spectra intensity. The modification of TiO₂ surface by lanthanum ion made it possible to enhance the photoactivity by retarding the recombination of photoexcited electron/hole pairs, in the result of the higher photoactivity in the stronger PL intensity.     

Influence of FCC catalyst steaming on HDPE pyrolysis product distribution

A commercial FCC catalyst based on a zeolite active phase has been used in the catalytic pyrolysis of HDPE. The experimental runs have been carried out in a conical spouted bed reactor provided with a feeding system for continuous operation. Different treatments have been applied to the catalyst to improve its behaviour. This paper deals with the optimization of catalyst steaming and pyrolysis temperature in order to maximize the production of diesel-oil fraction. The performance of the fresh catalyst has been firstly studied at 500 °C. This catalyst gives way to 52 wt% gas yield, 35 wt% light liquid fraction and a low yield of C₁₀⁺ fraction (13 wt%). After mild steaming (5 h at 760 °C) the results show a significant improvement in product distribution. Thus, gas yield decreases to 22 wt%, the yield of light liquid is similar to that of the fresh one (38 wt%), whereas the yield of the desired C₁₀⁺ fraction increases to 38 wt%. Nevertheless, the best results have been obtained when a severe steaming is applied to the catalyst (8 h at 816 °C) and pyrolysis temperature is reduced to 475 °C. There is a significant reduction in the gaseous fraction (8 wt%). The light liquid fraction has also been reduced to 22 wt%, but the yield of diesel fraction increases to 69 wt%. Moreover, the deactivation of the catalyst has also been studied under the optimum conditions.