The effect of boron addition on hydrodesulfurization and hydrodenitrogenation activity of NiMo/Al2O3 catalysts

Lewandowski, Marek; Sarbak, Z.

doi:10.1016/s0016-2361(99)00151-9

Cited by 83 publications

(40 citation statements)

References 11 publications

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“…Lewandowski and Sarbak (272) reported significant enhancement in activity for HDN of Q and CAR on the addition of boron (9.1 and 11.7% B 2 O 3 ) to sulfided NiMo/Al 2 O 3 catalyst. At the same time, no effect on HDS activity was observed.…”

Section: Vi16 Effect Of Other Additivesmentioning

confidence: 99%

Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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A high level of hydrodenitrogenation (HDN) is required to achieve a desirable conversion of other hydroprocessing reactions. This results from a strong adsorption of nitrogen-containing compounds on catalytic sites that slows down the hydrogen activation process and hinders the adsorption of other reactants. Studies on model compounds and real feeds indicate that less than 50 ppm of nitrogen in the feed can poison catalytic sites. Kinetic studies determined adsorption constants of various nitrogen-containing compounds and concluded that at least four different catalytic sites are required to interpret experimental observations in contrast with a dual site site ffi concept, which only considered two sites. The advancements in experimental techniques allowed identification of products formed during very early stages of hydrodenitrogenation. These results confirmed that the removal of the amino group from saturated amines, as the last step in hydrodenitrogenation, is governed by the type of carbon to which the amino group is attached rather than the number of hydrogen atoms attached to carbon in a and b position to nitrogen Performance of conventional Co(Ni)Mo(W)/Al 2 O 3 catalysts during hydrodenitrogenation was enhanced by combination with various additives and by replacing the traditionally used g-Al 2 O 3 support with novel supports. Catalytic functionalities could be modified by using different precursors of active metals and varying conditions during preparation. Progress has been made in the development of catalysts possessing a high selectivity for hydrodenitrogenation. In this case, the nonconventional catalysts based on the carbides and nitrides of transition metals exhibited high activity and selectivity. Noble metal sulfides alone or supported on different supports were active for HDN as well. Feedstocks used for catalyst evaluation included model compounds and mixtures of model compounds as well as real feeds. The challenges in the development of catalysts for hydrodenitrogenation of heavy feeds containing asphaltenes and metals have been identified.In general, compared to Q, conversions were little affected by a methyl (Me) on the aromatic ring, while being lower for Me on the N-ring, except for 2-MeQ. It is evident that Me substitution in the 2-position had little effect on HDN over the NiMoP/Al 2 O 3 catalyst, whereas it actually enhanced the HDN rate over the CoMo/Al 2 O 3 catalyst. For both catalysts the HDN rate was suppressed in 6-MeQ and particularly in 3-MeQ and 4-MeQ. The distribution of N-containing intermediates was influenced by the ring substitution and the type of catalyst. This suggests that several factors influence the overall HDN mechanism of Qs. This should be kept in mind while analyzing differences in the networks proposed by different authors.The preceding discussion on the HDN of Q mostly referred to conventional catalysts. A number of studies on the HDN of Q were conducted over unconventional catalysts. For example, 3-and 4-MeQs were more reactive than Q over the unsupported Zr,...

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Section: Vi16 Effect Of Other Additivesmentioning

confidence: 99%

Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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“…The larger desorption area, the greater the acid sites. In the figure, a peak between 150 and 250 • C was observed for all the catalysts indicating that weak-intermediate acid sites were present on the catalyst surface [42]. As clearly shown by the NH 3 -TPD profiles of the catalysts (presented in Figure 3), the intensity and area of desorption peaks gradually increased, reached maximum for 5Cu-3B/Al 2 O 3 with the increase of boron content, proving the increase in acidity of the catalyst surface [38].…”

Section: Catalyst Characterizationmentioning

confidence: 93%

Selective Hydrogenolysis of Glycerol and Crude Glycerol (a By-Product or Waste Stream from the Biodiesel Industry) to 1,2-Propanediol over B2O3 Promoted Cu/Al2O3 Catalysts

et al. 2017

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Abstract:The performance of boron oxide (B 2 O 3 )-promoted Cu/Al 2 O 3 catalyst in the selective hydrogenolysis of glycerol and crude glycerol (a by-product or waste stream from the biodiesel industry) to produce 1,2-propanediol (1,2-PDO) was investigated. The catalysts were characterized using N 2 -adsorption-desorption isotherm, Inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), ammonia temperature programmed desorption (NH 3 -TPD), thermogravimetric analysis (TGA), temperature programmed reduction (TPR), and transmission electron microscopy (TEM). Incorporation of B 2 O 3 to Cu/Al 2 O 3 was found to enhance the catalytic activity. At the optimum condition (250 • C, 6 MPa H 2 pressure, 0.1 h −1 WHSV (weight hourly space velocity), and 5Cu-B/Al 2 O 3 catalyst), 10 wt% aqueous solution of glycerol was converted into 1,2-PDO at 98 ± 2% glycerol conversion and 98 ± 2% selectivity. The effects of temperature, pressure, boron addition amount, and liquid hourly space velocity were studied. Different grades of glycerol (pharmaceutical, technical, or crude glycerol) were used in the process to investigate the stability and resistance to deactivation of the selected 5Cu-B/Al 2 O 3 catalyst.

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“…The effect of rGO on the acidity of catalysts is exhibited in Fig. 6a, the desorbed NH 3 below 105 o C is attributed to the physically absorbed NH 3 while the chemically absorbed NH 3 is desorbed between 105 and 610 o C. Based on the temperature at which adsorbed NH 3 desorbs, the acid sites are classified as weak (<230 o C), medium (230-430 o C) and strong (>430 o C) acid sites [47]. Obviously, an intensive desorption peak (marked in red circle) is observed in demonstrating the increase of medium acid sites and the type of acid will be discussed later.…”

Section: Ft-irmentioning

confidence: 99%