Silica-alumina Catalyst Research Articles

Hydrothermal Liquefaction of Microalgae to Bio-oil Using Zeolite Catalysts

Mesoporous zeolite silica-alumina catalysts were investigated for their impact on the hydrothermal liquefaction (HTL) to convert Nannochloropsis oculata into bio-oil. The commercial catalysts were characterized using characterization instruments which are XRD, SAP, and TPD-NH3 analysis, revealing distinctive structural and physicochemical properties. The catalytic screening was conducted at varied reaction temperatures (160–240 °C), durations (60–120 min), and catalyst loadings (1–5 wt.%). The result revealed that ZSM-5 demonstrates effectiveness as a catalyst for the HTL of Nannochloropsis oculata, yielding high bio-oil production under optimized conditions. Strong acid sites and high surface area density are highlighted as the key factors contributing to the catalyst's enhanced performance in promoting valuable bio-oil components.

Effect of acidity of solid acid catalysts during non-oxidative thermal decomposition of LDPE

AbstractThermal decomposition of low-density polyethylene (LDPE) was monitored by thermogravimetry under N2 atmosphere in the presence of solid acid catalysts such as alumina (α-Al2O3, γ-Al2O3), crystalline silica-alumina (SA, molar ratio of Si/Al = 0.19) and amorphous silica-alumina catalysts (ASA, molar ratio of Si/Al = 4.9). Crystal structure and surface area of solid acid catalysts were measured by XRD and BET, respectively. The strength and distribution of acid sites of solid acid catalysts were estimated by NH3-TPD. It was observed that total acidity strength is in the order of ASA (1.77 μmmol NH3/g) > AS (1.42 μmol NH3/g) > γ-Al2O3 (1.06 μmol NH3/g) > α-Al2O3 (0.06 μmol NH3/g). Thermal degradation behavior of LDPE with and without solid acid catalyst was monitored by TGA, where heating rates (β) of 5, 10, and 20 °C/min were employed under an inert atmosphere, and their activation energies (Ea), onset temperatures (Tinitial), decomposition temperatures (Tdecomp) were calculated and compared. The activation energy (Ea) was evaluated using the Coats-Redfern method. Solid acid catalysts with stronger acidity and higher surface area showed a decrease in activation energy and onset temperature. Activation energy of LDPE over ASA catalyst is decreased to 97.3 kJ/mol from thermal decomposition of LDPE without catalyst of 117.2 kJ/mol under heating rate of 10 °C/min. The isothermal decomposition of LDPE was monitored at 300 °C for 3 h with a heating rate of 10 °C/min, where 13.1% and 24.2% wt. loss were observed over SA and ASA, respectively, while only 0.7% wt. loss was observed for LDPE without a solid acid catalyst. Graphical abstract Single step decomposition of LDPE Thermal degradation behavior of LDPE monitored by TGA, with different heating rates (β) of 5, 10, 20 °C/min.

Catalytic pyrolysis of waste high-density (HDPE) and low-density polyethylene (LDPE) to produce liquid hydrocarbon using silica-alumina catalyst

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% wax-like hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GC-MS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. J. Bangladesh Acad. Sci. 47(2); 195-203: December 2023

Production of high-carbon-number bio-aviation fuels from furans using sulfated zirconia and silica-alumina aerogel catalysts

Lignocellulose can help produce fuels in biorefineries through its fractionated components such as cellulose, hemicelluloses, and lignin. For instance, hemicellulose-derived xylose has been studied for obtaining petroleum-substituting fuels. Therefore, in this study, catalytic hydroalkylation/alkylation (HAA) of xylose-derived 2-methylfuran (2-MF) with butanal was targeted to selectively produce high-carbon-number diesel fuels. To that end, silica–alumina (SiAl) aerogels with different Si/Al ratios and a series of sulfated zirconia (SZ) compounds calcined at various temperatures were prepared as catalysts to overcome the limitations of conventional hazardous homogeneous acid catalysts. The activity of the SiAl catalysts in forming the desired HAA product, 5,5-bissylvylbutane (denoted as BB), was found to be directly related to the number of acid sites and acid density. Moreover, increasing the Si/Al molar ratio, which reduced the acid density and number of acid sites, led to lower 2-MF conversions and BB yields. The optimal 2-MF conversion and BB yield with the SiAl catalysts (67 % and 45 %, respectively) were achieved using a Si/Al ratio of 8:2 mol/mol. Furthermore, SZ calcined at 700 °C (denoted as SZ-700) exhibited the highest activity among the SZ catalysts (72 % 2-MF conversion, 63 % BB yield), despite having the fewest acid sites and lowest acid density. This was presumably because of the physical structure of SZ-700, which featured mixed monoclinic and tetragonal phases, many oxygen vacancies, and a large accessible external surface area, which facilitated the HAA reactions. Hydrogenation and hydrodeoxygenation (HDO) of BB were performed thereafter using Pd/C and Ru/SiO2–Al2O3 catalysts, respectively. The resulting deoxygenated hydrocarbons comprised 15.1 % light hydrocarbons (C4–C8) and 83.1 % heavier hydrocarbons (C9–C20). Simulated distillation analysis of the post-HDO product distribution indicated that the liquid-phase product contained 70 % high-carbon-number bio-aviation fuels.

Conversion of Cellulose to 5-HMF in the Presence of Silica-Alumina Catalysts Synthesized by Dual Template at Low Temperature

In this study, which incorporates many principles of green chemistry (use of renewable feedstocks, catalysis, improvement of energy efficiency, and harmless solvents and auxiliaries), the single-phase catalytic conversion of cellulose to 5-HMF in over silica-alumina catalysts was investigated. A series of dual-template silica-alumina catalysts with CTAB as the main template and F127 or triethylamine (TEA) as the co-template were synthesized at a low temperature of 60 °C and characterized by XRD, N2 adsorption-desorption technique, FT-IR and pyridine adsorption FT-IR. The surface area is increased by using the second template in silica-alumina catalyst. In addition, the acidity of the surface was changed by using the second template. The cellulose conversion and yield of 5-HMF increased from 36% to 52% and from 3.13% to 4.24%, respectively, due to the properties gained by using the second template. 52% cellulose conversion and 8.13% selectivity of 5-HMF were obtained in aqueous medium, 220 °C and 6 h reaction time with the catalyst using TEA as co-template. Eco-friendly silica catalysts synthesized at low temperatures with a dual template can be considered as a potential alternative for the conversion of cellulose into value-added biobased products.

Effect of promoters (Ce, Sr, Cs, and Sm) on the activity and coke formation of FSA support Ni in the dry reforming of methane

Methane dry reforming was employed to evaluate the Ni/Fibrous Silica-Alumina catalyst promoted with Cs, Ce, Sr, and Sm. The catalysts were prepared via impregnation followed by the hydrothermal method. X-ray diffraction, Brunauer-Emmett-Teller, Fourier-transform infrared spectroscopy, temperature programmed reduction, Raman, and thermogravimetry Analysis with derivative techniques were employed to characterize them. The results exhibited that adding Cs, Ce, Sr, and Sm promotion reduced the surface area of the catalyst. The consequence of introducing the promoters positively affected the performance of the catalyst. Therefore, the incorporation of Cs with Ni/FSA enhanced the long-term activity throughout the 50 h. The temperature programmed reduction assessment revealed that the addition of Cs improved the reducibility of the Ni catalyst and dropped the reduction temperature of NiO species. Moreover, the Cs-Ni/FSA showed the lowest amount of carbon located among all specimens via thermogravimetry analysis. Cs seems to be the most effective at preventing the formation of carbon, owing to its oxidation property which assists to rid the carbon and renders the durability of the catalyst.

Comparison of various catalysts in pyrolysis process: A review

The existence of polarity between production and recycling rates, as well as extravagant fossil fuel consumption has has led to the development of waste plastic to fuel conversion technology. Pyrolysis technology shows great potential in recovering liquid oil from plastic waste through thermal and catalytic degradation processes. Catalytic pyrolysis process has advantages over thermal degradation in terms of energy consumption, reaction time and oil grade. The choice of catalyst plays a dominant role in determinating reaction temperature, time, and product distribution. This paper reviews various types of catalysts, including fluid cracking catalyst (FCC), zeolites based catalysts, silica-alumina catalysts, and reforming catalysts, and the impact of various parameters include the mode of contact with plastic solid wastes - direct phase contact of catalyst (either liquid or solid), and vapor phase contact of catalyst, choice of catalyst, catalyst to polymer ratio, and acid-base nature of the catalyst on the product dispersion. The product distribution obtained from catalytic pyrolysis of different types of plastics such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyvinylchloride using ZSM – 5 and red mud catalysts at different temperatures are as follows: 56.9 wt%(liquid), 40.4 wt%(gases), 3.2 wt%(char) at 450 0C in the presence of 10 wt% of Zeolite Socony Mobil − 5 (ZSM – 5) catalyst and 57 wt% (liquid), 41.3 wt% (gases), 1.7 wt% (char) at temperature 500 0C in the presence of 10 wt% of red mud as a catalyst. When catalytic pyrolysis is applied to municipal plastic waste (a heterogenous plastic waste) using 50% natural zeolite as a catalyst at 450 0C the distribution is 50 wt% (liquid), 34 wt% (gases), and 16 wt% of char Although there is a negligible difference in the product distribution of thermoplastics, the use of red mud as a catalyst results in increased energy consumption., highlighting the impact of the acidic and basic characteristics of catalysts. In case of heterogenous feedstock i.e., mixed plastic highly acidic catalysts are used to achieve the desired product distribution.

Highly stable amorphous silica-alumina catalysts for continuous bio-derived mesitylene production under solvent-free conditions

Amorphous silica-alumina are efficient and highly stable catalysts for the continuous production of biomass-derived aromatics such as mesitylene from acetone, thus adding to the potential for value creation in biorefineries.

Catalytic Pyrolysis of Plastic Waste and Molecular Symmetry Effects: A Review

The present review addresses the latest findings and limitations in catalytic pyrolysis for the processing of plastic waste into valuable fuels. Compared to thermal degradation of plastics, catalytic pyrolysis provides better results in regards to the quality of the obtained liquid hydrocarbon fuel. Different types of catalysts can be used in order to improve the thermal degradation of plastics. Some of the most used catalysts are different types of zeolites (HUSY, HZSM-5, Hβ), Fluid Catalytic Cracking (FCC), silica-alumina catalysts, or natural clays. There is a need to find affordable and effective catalysts in the aim of achieving commercialization of catalytic pyrolysis of plastic waste. Therefore, this study summarizes and presents the most significant results found in the literature in regards to catalytic pyrolysis. This paper also investigates the symmetry effects of molecules on the pyrolysis process.

GC-MS analysis of hydrocarbons formed after catalytic cracking of heavy oil

The heavy oil from the Mordovo–Karmalskoye oil field is cracked in the presence of silica-alumina Al-Si catalyst and Al-Si catalyst modified with NiCrWC. The composition of saturated and aromatic compounds before and after catalytic cracking is studied. It is shown that in the presence of a modified NiCrWC/Al-Si catalyst, the destruction reactions resin-asphaltene components proceed more intensively than during cracking in the presence of Al-Si. Transformations of hydrocarbons during cracking of heavy oil in the presence of NiCrWC/Al-Si catalyst are more intensive as evidenced by the predominance of low-molecular homologues of normal and iso-structure alkanes over high-molecular ones and increased contents of C7–C10 alkylbenzenes, unsubstituted naphthalene, and methylnaphthalenes. This catalyst contributes to the complete decomposition of high-molecular cyclanes, mono- and trinaphthenoarenes. It has been shown that NiCrWC/Al-Si catalyst the formation of a larger amount of low-molecular-weight n-alkanes compared to high-molecular ones.

The preferable Ni quantity to boost the performance of FSA for dry reforming of methane

The spherical mesoporous Ni/fibrous silica-alumina (Ni/FSA) catalysts with varied Ni loadings (5–15 wt%) were effectively synthesized via hydrothermal method followed by impregnation method and catalytically evaluated through employing dry methane reforming. The XRD and FESEM mapping assessment demonstrated that the FSA has structural robustness independent of Ni loading quantities, and the NiO nanocrystalline size relies on the quantity of Ni loading. The mapping of FESEM images demonstrated the dispersion of Ni nanoparticles across the spherical form FSA, with 12.5Ni/ FSA exhibiting the most homogeneous distribution. The BET report indicated that when Ni loading was increased, the surface area of the catalysts increased to 645 m2/g via 12.5 % of Ni. However, in the case of 15Ni/FSA, Ni agglomeration was found. 12.5Ni/FSA gave the highest catalytic efficiency and stability (XCO2 = 82.16 %, XCH4 = 97.16 %, and H2/CO = 0.91). The stability test revealed no trace of deactivation after 60 h of time-on-stream. In concordance with the spent catalyst, XRD, Raman, and TGA investigations showed the graphitic carbon nonattendance for all spent Ni/FSA specimens, and the medium basicity noted by IR-pyrrole analyses, could be attributed to enhanced efficiency of the catalyst. According to the enhanced performance of 12.5Ni/FSA, there was a substantial synergistic impact between the Ni active metal sites and the FSA support, which boosted the reactivity based on both gaseous reactants, CH4 and CO2. The 12.5 wt% Ni was determined to be the optimum Ni value for inhibiting coke deposition on the FSA and hence improving catalytic performance.

Production of hydrocarbon fuels by heterogeneously catalyzed oligomerization of ethylene: Tuning of the product distribution

In the field of gasoline synthesis from renewable resources, highly integrated procedures with a minimum of process steps are mandatory to ensure efficient and sustainable production as well as marketability. In this context, oligomerization of ethylene to gasoline-type hydrocarbons is a viable option. The reaction has been studied employing a nickel silica-alumina catalyst and focusing on the influence of temperature, pressure, space velocity and time on stream on the product spectrum. Temperature and pressure largely influenced selectivity and intramolecular branching. The catalyst showed a stable performance during 170 h at 120 °C, 50 bar ethylene partial pressure and a space velocity of 8 h−1. Under these conditions, ethylene conversion was steadily beyond 99%. Selectivity to C6, C8, C10 and C12 fractions was 15%, 25%, 18% and 10% while the average content of iso-olefins was 24%, 85%, 94% and 96%, respectively. The product selectivity slightly changed with increasing time on stream leading to less branched oligomers, probably due to slight catalyst deactivation. To evaluate the suitability of the C5-12 fraction for fuel applications, it was hydrogenated and parameters like density, lower heating value, boiling behavior, vapor pressure, viscosity, flashpoint, autoignition temperature and oxidation stability have been determined.

Steam catalytic cracking of crude oil over novel hierarchical zeolite–containing mesoporous silica–alumina core-shell catalysts

The direct conversion of crude oil to basic chemicals was studied over novel core-shell structured ZSM-5 zeolite containing mesoporous silica-alumina (MSA) composites. A template-directed sol-gel method in an alkaline medium was used to prepare a core-shell structured ZSM-5 containing MSA composites employing CTAB as template, tetraethyl orthosilicate (TEOS), and aluminum sulfate. This approach resulted in the formation of a uniform mesoporous silica-alumina shell around the zeolite crystal. The shell thickness (tune in the 8–26 nm range) and its alumina content were controlled by varying the TEOS/zeolite and TEOS/aluminum sulfate ratios. The physicochemical properties and steam catalytic cracking performance of Arab Extra Light (AXL) crude oil were investigated to enhance the yield of C2-C4 light olefins. For comparative study, conventional and mesoporous silica-alumina composites were mixed with kaolin (50%), steam deactivated (810 °C for 6 h) and tested in a fixed-bed reactor operated at 675 °C, residence time of 10 s and steam/oil ratio (g/g) of 0.5. The optimized mesoporous silica-alumina composite Z30 @ MSA (TEOS/zeolite = 0.85 and TEOS/aluminum sulfate = 15.86) had improved textural characteristics, moderate acidity, and AXL crude oil cracking potential at higher conversion (~70%) and selectivity towards light olefins (49.4%) than the unmodified ZSM-5(30). The mesoporous core-shell composite's distinct reaction pattern resulted in the formation of a unique mesoporous silica-alumina core-shell catalyst, which eased the rapid diffusion of desired products from intra-framework channels while inhibiting the formation of coke deposits.

Hydrolytic vs. Nonhydrolytic Sol-Gel in Preparation of Mixed Oxide Silica–Alumina Catalysts for Esterification

The development of green and sustainable materials for use as heterogeneous catalysts is a growing area of research in chemistry. In this paper, mesoporous SiO2-Al2O3 mixed oxide catalysts with different Si/Al ratios were prepared via hydrolytic (HSG) and nonhydrolytic sol-gel (NHSG) processes. The HSG route was explored in acidic and basic media, while NHSG was investigated in the presence of diisopropylether as an oxygen donor. The obtained materials were characterized using EDX, N2-physisorption, powder XRD, 29Si, 27Al MAS-NMR, and NH3-TPD. This approach offered good control of composition and the Si/Al ratio was found to influence both the texture and the acidity of the mesoporous materials. According to 27Al and 29Si MAS NMR analyses, silicon and aluminum were more regularly distributed in NHSG samples that were also more acidic. Silica–alumina catalysts prepared via NHSG were more active in esterification of acetic acid with n-BuOH.

Hydrocracking of Heavy Vacuum Gas Oil with Petroleum Wax

Petroleum heavy vacuum gas oil (HVGO) containing 10 wt.% of petroleum wax was hydrocracked at 390–430 °C and under the pressure of 18 MPa over a Ni W/amorphous silica-alumina catalyst in a continuous-flow fixed-bed reactor. The hydrocracking of a reference feed (neat HVGO) was carried out under the same reaction conditions. The physico-chemical properties of primary products obtained via laboratory atmospheric-vacuum distillation (heavy naphtha, middle distillates and distillation residue) were evaluated. Most products prepared from the mixed feedstock had a similar or lower density and sulfur content than the products obtained from the hydrocracking of the neat HVGO. The heavy naphtha fractions obtained from mixed feedstock contained slightly more n-alkanes and iso-alkanes and less naphthenes and aromatics. Similarly, middle distillates obtained from the mixed feedstock contained slightly more n-alkanes and less aromatics and had cetane index higher by up to 2 units.

Transition metal chalcogenide bifunctional catalysts for chemical recycling by plastic hydrocracking: a single-source precursor approach.

Sulfided nickel, an established hydrocracking and hydrotreating catalyst for hydrocarbon refining, was synthesized on porous aluminosilicate supports for the hydrocracking of mixed polyolefin waste. Zeolite beta, zeolite 13X, MCM41 and an amorphous silica-alumina catalyst support were impregnated with the single-source precursor (SSP) nickel (II) ethylxanthate for catalyst support screening. Application of this synthesis method to beta-supported nickel (Ni@Beta), as an alternative to wet impregnation using aqueous nickel (II) nitrate, provided catalytic materials with higher conversion to fluid products at the same mild batch reaction conditions of 330°C with appropriate agitation and 20 bar H2 pressure. Mass balance quantification demonstrated that SSP-derived 5wt%Ni@Beta yielded a greater than 95 wt% conversion of a mixed polyolefin feed to fluid products, compared with 39.8 wt% conversion in the case of 5wt%Ni@Beta prepared by wet impregnation. Liquid and gas products were quantitatively analysed by gas chromatography–flame ionization detection (GC-FID) and gas chromatography–mass spectrometry (GC-MS), revealing a strong selectivity to saturated C4 (37.3 wt%), C5 (21.6 wt%) and C6 (12.8 wt%) hydrocarbons in the case of the SSP-derived catalyst.

Influence of retarded injection timing on thermal performance and emission characteristics of a diesel engine fuelled with an optimized pyrolytic blend

The enormous rise in plastic waste leads to severe environmental issues and complete removal is a quiet challenge. The entire world focuses on finding new alternate for traditional conventional fuel. The waste low-density polyethylene is chosen as feedstock for the preparation of fuel from thermo-catalytic pyrolysis, considering the silica–alumina catalyst at a reaction temperature of 500 °C. From our previous study, the lower blends of waste low-density polyethylene exhibit a similar performance to diesel. However, brake thermal efficiency and oxides of nitrogen are not encouraging. Further improving combustion behaviour, the present research is carried out at different injection timings. The investigation is carried on standard injection timing of 23°bTDC and three retarded injection timings, namely, 21°bTDC, 19°bTDC and 17°bTDC. Retarded injection timing exhibits higher performance and lower unburned hydrocarbon, oxides of nitrogen and carbon monoxide emissions. However, smoke emission is increased due to the reduced heat release at all the considered test parameters. The result divulges that reduced performance and increased smoke at 17°bTDC due to the lack of burning rate. The combustion behaviour of 20% waste low-density polyethylene by volume at 19°bTDC is similar to that of diesel at 23°bTDC. Hence, the injection timing of 19°bTDC is preferred as an optimized condition for the test fuel 20% waste low-density polyethylene by volume.

Causes of deactivation of an amorphous silica-alumina catalyst used for processing of thermally cracked naphtha in a bitumen partial upgrading process

Thermally cracked naphtha represents a challenging feed for many catalytic processes. Its contaminant content and reactivity cause the deactivation of catalysts. Nevertheless, the use of an amorphous silica-alumina acid catalyst to convert and reduce the alkene content in thermally cracked naphtha was possible. The purpose of this study was to determine the cause(s) of catalyst deactivation by analysis of spent catalysts after conversion of cracked naphtha at different conditions in the range 250–350 °C, 6 MPa and WHSV of 0.5–2 h−1. It was found that nitrogen bases, suspected to be important acid catalyst poisons, were not the main cause of catalyst deactivation. Nitrogen was more abundant in deposits on the catalyst at the inlet compared to the outlet of the reactor, but the accumulated nitrogen in deposits represented only a minor fraction of the total amount of basic nitrogen to which the catalyst was exposed. Carbonaceous deposits were the main cause of catalyst deactivation and the profile of the deposition on the catalyst changed with temperature. At 325 °C the amount of deposits at the reactor outlet was higher, with lower H/C ratio and higher persistent free radical content than at the reactor inlet. Although some of the precursor species that formed deposits were present in the feed, some of the precursor species that formed deposits were produced during the conversion process. Although the contribution of acid catalysis was not ruled out, many observations in the study indicated that carbonaceous deposits formed mainly due to free radical reactions.

Synthesis of 2, 4 disubstituted 1, 5 benzodiazepines promoted by efficient Silica-Alumina Catalyst

An efficient and environment friendly valuable synthon of 1, 5 benzodiazepine derivatives were synthesized having unique physical and medicinal properties. This reaction is performed by mesoporous binary mixed metal oxide SiO2-Al2O3 which is synthesized by hydrothermal method at high temperature. This mesoporous material is investigated by XRD, SEM, EDS, TEM, TPD and BET surface area. Present method offers several remarkable advantages such as non-toxic, noncorrosive and easy work-up procedure for the purification of product with non-chromatographic method, ecofriendly reaction condition.

Biochar from Slow Catalytic Pyrolysis of Spirulina platensis Residue: Effects of Temperature and Silica-Alumina Catalyst on Yield and Characteristics

The use of biochar varies on its ability as an adsorbent which adsorbs liquid or gas molecules. Biochar from Spirulina platensis residue (SPR) as an energy source, as its richness in nutrients, can be used as fertilizer and maintain water resources in plantations. Biochar can be used as an intermediary for the synthesis of nanotubes, activated carbon, carbon black, and carbon fiber. One of the essential things to be considered in the application of activated carbon from SPR is char’s characteristics. This study aimed to obtain data on the biochar and components from the pyrolysis of Spirulina platensis residue. The study was conducted in a fixed-bed reactor with electric heaters with a variety of temperatures (300-700 ⁰C) and the amount of silica-alumina catalyst (0-20%). The biochar weight was obtained by weighing the char formed at the end of the pyrolysis. The char characteristics were obtained by the surface area, total pore volume, and pore size analysis. Based on the study results, the relationship between temperature and the amount of catalyst on the characteristics of biochar was studied. The higher the pyrolysis temperature, the less biochar. Also, the use of catalysts can reduce the amount of biochar. The higher the temperature, the higher the surface area and the total pore volume while the pore radius was reduced. The optimum condition for maximum biochar yield in non-catalytic pyrolysis at a temperature of 300 ⁰C was 49.86 wt.%. The surface area, the total pore volume, and the pore radius at 700 ⁰C catalytic pyrolysis with 5% silica-alumina was obtained as 36.91 m2/g, 0.052 cm3/g, and 2.68 nm, respectively.Keywords: biochar; pore radius; silica-alumina; surface area; total pore volumeA B S T R A KPenggunaan biochar bervariasi pada kemampuannya sebagai adsorben dalam menjerap molekul cairan atau gas. Biochar dari residu Spirulina platensis merupakan sumber energi, karena kaya akan unsur hara, dapat digunakan sebagai pupuk dan pemeliharaan sumber daya air di perkebunan. Biochar dapat juga digunakan sebagai perantara untuk sintesis nanotube, karbon aktif, carbon black, dan serat karbon. Salah satu hal penting yang harus diperhatikan dalam aplikasi karbon aktif dari SPR adalah karakteristik arang. Penelitian ini bertujuan untuk mendapatkan data biochar dan komponen dari pirolisis residu Spirulina platensis. Penelitian dilakukan di reaktor fixed-bed dengan pemanas listrik dengan variasi suhu (300-700 ⁰C) dan jumlah katalis silika-alumina (0-20%). Berat biochar diperoleh dengan cara menimbang arang yang terbentuk pada akhir pirolisis. Sedangkan karakteristik arang diperoleh dari analisis luas permukaan, volume pori total, dan ukuran pori. Berdasarkan hasil studi hubungan antara suhu dan jumlah katalis terhadap karakteristik biochar yang telah diteliti, semakin tinggi suhu pirolisis maka biochar semakin sedikit. Selain itu, penggunaan katalis dapat mengurangi jumlah biochar. Sebaliknya, semakin tinggi suhu semakin besar luas permukaan, dan volume pori total serta radius pori-pori semakin berkurang. Kondisi optimum untuk biochar maksimum pada pirolisis non katalitik pada suhu 300 ⁰C adalah 49,86 wt.%. Luas permukaan, total volume pori, dan radius pori pada suhu 700 ⁰C untuk pirolisis katalitik silika-alumina 5% diperoleh masing-masing sebesar 36,91 m2/g, 0,052 cm3/g, dan 2,68 nm.Kata kunci: biochar; luas permukaan; radius pori; silika-alumina; total volume pori