Selective Catalytic Reduction of NO by NH3 over Mn–Cu Oxide Catalysts Supported by Highly Porous Silica Gel Powder: Comparative Investigation of Six Different Preparation Methods

In this study, Mn-based catalysts supported by highly porous silica gel powder (SSA up to 470 m2·g−1 and total pore volume up to 0.8 cm3·g−1) were prepared by six different methods in liquid solutions (electroless metal deposition, stepwise addition of a reducing agent, wet impregnation, incipient wetness impregnation, urea hydrolysis, and ammonia evaporation) and tested for selective catalytic reduction of NOx with ammonia (NH3-SCR de-NOx). Prior to the activity test all the catalysts prepared were characterized by ICP-OES, SEM, EDX mapping, XPS, XRD and N2 adsorption techniques to provide the comprehensive information about their composition and morphology, investigate the dispersion of active components on the carrier surface, identify the chemical forms and structural properties of the catalytically active species of the catalysts prepared. The results revealed that all the methods applied for preparation of SCR de-NOx catalysts can ensure the uniform distribution of Mn species on the carrier surface, however as it is typical for preparation techniques in a liquid phase the significant reduction in SSA and pore volume along with increasing the loading was observed. Considering both the physicochemical properties and the catalytic performance of the catalysts the least effective preparation method was shown to be ammonia evaporation, while the most attractive techniques are incipient wetness impregnation and electroless metal deposition.

Biogas Reforming over Al-Co Catalyst Prepared by Solution Combustion Synthesis Method

The results of carbon dioxide reforming of CH4 (model biogas) on catalysts prepared by solution combustion synthesis (SCS) and impregnation of moisture capacity methods are presented. Investigation of the activity of catalysts synthesized from initial mixtures of Co(NO3)2-Al(NO3)3-urea of different compositions was carried out for the production of synthesis-gas, and SCS and traditional incipient wetness impregnation catalyst preparation methods were compared. The methane conversion reached 100%, and the conversion of CO2 increased to 86.2%, while the yield of H2 and CO was 99.2% and 85.4%, respectively, at 900 °C. It was found that CoAl2O4 spinel formation was due to substitution of Al3+ with Co2+ cations. Consequently, CoAl2O4 lattice parameters increased, since the ionic radius of Al3+ (0.51 Å) less than Cο2+ (0.72 Å). Advantages of SCS catalysts in comparison with catalysts prepared by the traditional incipient wetness impregnation method in dry reforming of methane were shown. The aim of this work is to develop a new catalyst for the conversion of model biogas into synthesis gas, which will contribute to the organization of a new environmentally friendly, energy-saving production in the future.

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

The catalytic production of syngas by the partial oxidation of methane (POM) was investigated over Pd supported on ceria (0.5–2 Pd wt.%) prepared by incipient wetness impregnation and by mechanochemical methods. The performance of the Pd/CeO2 catalyst prepared by milling CeO2 and Pd acetate was superior to that prepared by milling CeO2 and Pd nitrate and to Pd/CeO2 prepared by impregnation from Pd acetate. The best catalytic activity of the Pd/CeO2 catalyst prepared from CeO2 and Pd acetate was obtained by milling at 50 Hz for 5 min. Two-step combustion and reforming reaction mechanism were identified. Remarkably, methane conversion increased progressively with Pd loading for the catalysts prepared by incipient wetness impregnation, whereas low metal loading showed better conversion of methane for the catalysts prepared by ball milling using Pd acetate. This was explained in terms of an impressive dispersion of Pd species with a strong interaction with the surface of ceria, as deduced from transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy characterization, which revealed a large quantity of highly oxidized species at the surface.

Phosphorus Promoted HZSM-5 Zeolites for the Coupling Transformation of Methanol with 1-Butene to Propylene

Phosphorus promoted HZSM-5 zeolites (P-HZSM-5) were prepared by synthetic methods of incipient wetness impregnation and in-situ synthesis, respectively. It was characterized by the means of XRD, SEM, BET, TG and NH3-TPD. The P-HZSM-5 zeolite prepared by incipient wetness impregnation has a large specific surface area and pore size, and the weak acidity is remarkably increased. The catalytic activity of P-HZSM-5 for the coupling transformation of methanol with 1-butene to propylene was investigated. Under the reaction conditions of temperature at 550 ℃, pressure at 0.4 MPa, space velocity at 1800 mL/(gcath) and mole ratio of CH3OH/C4H8 to 1:1, the conversion of C4H8 can reach to 75.8%, and the selectivity and yield of propylene are 42.2% and 31.9%, respectively.

Kinerja Katalis Ni-Cu/HZSM-5 dalam Pembuatan Biogasoil dari Minyak Bintaro (Cerbera Manghas) dengan Proses Hydrocracking

Catalytic cracking dan hydroprocessing merupakan dua proses yang digunakan untuk mengubah minyak nabati menjadi biofuel, gabungan dari kedua proses tersebut dinamakan reaksi hydrocracking. Minyak bintaro yang bersifat non-edibleoil serta memiliki kadar minyak cukup banyak yakni sebesar 35-50% dapat direkomendasikan sebagai salah satu sumber minyak nabati yang dapat diolah menjadi biogasoil. Penambahan logam nikel (Ni) dan tembaga (Cu) ialah untuk memperoleh yield yang lebih baik daripada menggunakan satu jenis katalis. Preparasi katalis dilakukan dengan menggunakan metode incipient wetness impregnation. Variabel loading support HZSM-5 yang digunakan sebesar 5% dan 10%, serta ratio logam Ni-Cu yaitu 1:1. Katalis Ni-Cu/HZSM-5 dianalisa menggunakan BET, EDX, dan XRD untuk mengetahui karakteristik katalis. Selanjutnya proses hydrocracking dilakukan dengan mencampurkan 2 gram katalis Ni- Cu/HZSM-5 dan 250 ml minyak bintaro ke dalam reaktor batch berpengaduk pada suhu reaksi 375 ̊C selama 2 jam. Produk cair (biofuel) yang dihasilkan dari proses hydrocracking dianalisa menggunakan GC-MS untuk mengetahui komposisi hidrokarbon. Rute reaksi yang mendominasi dalam penelitian ini ialah reaksi dekarbinolasi dan dekarboksilasi. Hal itu terlihat dari komposisi hidrokarbon terbanyak dari produk biogsoil yang dihasilkan ialah C15 dan C17. Hasil dari penelitian diperoleh Ni-Cu/HZSM-5 dengan loading 5% dan ratio logam 1:1 optimum digunakan pada proses hydrocracking minyak bintaro untuk menghasilkan biogasoil dengan yield sebesar 82,7%.

Conversion of biomass-derived oil over promoted ZSM-5 based catalysts

Crude canola oil was thermo-catalytically converted to unsaturated hydrocarbons and aromatics. The major products were: 1,5-Heptadien-3-yne, 1,3-Hexadien-5-yne, 1- ethenyl-3-methylene-cyclopentene and Xylenes for Ni-ZSM-5, Benzene, Toluene, and other Aromatics including Ethylbenzene for Sn-ZSM-5 samples. The preparation of Ni and Sn-HZSM-5 was achieved by calcining the commercial NH4-ZSM-5, Si/Al ratio of 50, and promoting the material with Ni and Sn chlorides. Various techniques were used to promote the catalysts, namely, mechanical mixing promotion (MM), incipient wetness promotion (IW) and aqueous promotion (AQ). All the reactions were carried out at a WHSV of 10.6 hr-1 and temperature of 450°C. A fixed bed reactor system was used. To understand the reactions involved in the process, the characterization of the feed was done by GC-FID to identify the fatty acid composition of the Canola oil. The analysis showed that the feed was mainly composed of C18-16 fatty acids. The Gas products were characterized by GC-TCD and revealed the presence of C1 gases: CO, CO2 and CH4. No H2 was detected in the gas products. The selectivity in the gas fraction was barely influenced by the composition of the HZSM-5 based samples and the results show a mean difference within ±1.0%. A fractional conversion of close to 100% for all the tested Ni-loaded samples was observed, no fatty acids were detected in the OLP. Since the detected C18-16 fatty acids are liquids at room temperature, it was concluded that the amount of C18 fatty acids in the gas product was zero. When the HZSM-5 was loaded with Sn (atomic radius = 145pm), at higher loading %, (2.99 and 3.82%) of Sn, the conversion was lowered up to 77.9 and 91.4% from 100% that was observed for lower loading of 0.25 – 1.77%. The organic liquid product fraction was characterized using GC-MS. An analysis was done for the thermo-catalytic products of six different groups of catalysts, namely: Ni- Aqueous promotion; Ni-AQ, Ni-Incipient Wetness promotion Ni-IW; Ni-Mechanical Mixing promotion; Ni-MM; Sn-Aqueous promotion; Sn-AQ, Sn-Incipient Wetness promotion; Sn-IW, and Sn-Mechanical Mixing promotion; Sn-MM. Each of these different metal loading/ promotions were done to understand how the products were affected by increasing the Metal Loading/ promotion. For each of the product streams, the metal loading/ promotion targets of 0.5%, 1%, 3%, 5% and 7% were used. Trends to relate the Metal loading/ promotion to the product output and fractional conversion were done for each metal for comparison of the different product streams. It was observed that for Ni-AQ, Ni-IW and Ni-MM the average amount of aromatics in the organic liquid product for the Metal loading/ promotion was 68.3%, 80.6% and 63.3% respectively. From results it was observed that the activity of the Sn loaded samples increases in the production of various products groups such as Benzene, Toluene and Xylene (BTX) among other aromatics and, Ni activity was more towards Cyclopentane derivatives and Alkynes (XCA). The unpromoted commercial HZSM-5 catalyst produced 7.18% Xylenes, with no Cyclopentane Deravatives and Alkynes detected. Ni-loading exhibited increased catalytic activity towards XCA production for samples loaded using AQ and MM techniques. The samples loaded by IW technique showed activity towards producing Xylene but not Cyclopentane Derivatives or Alkynes. The introduction of Ni has increased the production of unsaturated hydrocarbons lighter than the C18 hydrocarbons such as: 1,5-Heptadien-3-yne, 1,3-Hexadien-5-yne, and 1- ethenyl-3-methylene-cyclopentene. The results obtained from this study show the selectivity toward BTX and other aromatics was lifted when HZSM-5 was promoted with Sn in comparison to the unpromoted HZSM-5 and Ni-HZSM-5. No Cyclopentane Derivatives and Alkynes were detected in any of the products of the Sn loaded samples.

Influence of the Preparation Method of Ag-K/CeO2-ZrO2-Al2O3 Catalysts on Their Structure and Activity for the Simultaneous Removal of Soot and NOx

Ag/CeO2-ZrO2-Al2O3, a known catalyst for the simultaneous removal of NOx and soot, was modified by the addition of K, and was prepared using various techniques: wet impregnation, incipient wetness, and chemical vapor impregnation at different temperatures. The effect of the preparation method on catalyst activity was studied. It was found that catalysts prepared via wet impregnation, incipient wetness, and chemical vapor impregnation at 80 °C were able to utilize in situ formed N2O at low temperatures, to simultaneously remove NOx and soot. The difference in preparation method affected the catalyst’s ability to produce and use N2O as an oxidant for soot. The temperature at which chemical vapor impregnation was performed greatly influenced the catalyst’s ability to oxidize soot. The introduction of K to the Ag/CeO2-ZrO2-Al2O3 vastly improved the soot oxidation activity, particularly for the catalyst prepared via wet impregnation. However, the incorporation of K had an adverse effect on the reduction of NOx.