Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts

Abstract

BACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon-neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H-ZSM-5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds.RESULTS: Successive addition of Fe and P to the H-ZSM-5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co-addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on-stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air.CONCLUSION: Fe-and/or P-modified H-ZSM-5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air.

Tuning of product selectivity in the conversion of ethanol to hydrocarbons over H-ZSM-5 based zeolite catalysts

“…2. All samples exhibited typical H-ZSM-5 zeolite structure without the appearance of any new peak, suggesting that no additional crystalline phases are detectable, as reported previously [24,32]. The intensity of XRD patterns significantly decreases after addition of phosphorus, in particular the main peak at 23.2°of 6PZ reduces slightly half of intensity in comparison with parent zeolite, due to the framework defects caused by dealumination [33,34].…”

Ethylene Production from Ethanol Over Metal/Phosphorus-Modified ZSM-5 Catalysts

“…39 In general, the selectivity of each product changed with time-on-stream. As to ethylene, its selectivity had a drastic increase during reaction on all modified HZSM-5.…”

On the use of infrared spectrometer as detector for Temperature Programmed (TP) techniques in catalysts characterization

“…35 According to the literature, TPD can be performed by a wide 36 variety of methods: the analyses of the outlet gas stream with 37 techniques such as mass spectroscopy [11,12], thermal conductivi- 38 ty detectors (TCD) [12][13][14], flame ionization detectors (FID) [12], or 39 a combination of infrared and mass spectrometry (IRMS) detectors 40 [10,15,16]. Alternatively, the heat flow curve is acquired during 41 this process and the amount of desorbed species as a function of 42 time is measured either by mass variation, using a microbalance 43 [11,17,18], or by particular systems such as a Quantachrom 44 Autosorb-1 instrument [19], NH 3 -TPD apparatus (Nihon Bell, 45 Japan, BEL-CAT) connected to a Q-Mass analyser (Pfeiffer Vacuum, 46 Omnistar GCD301, Germany) [20]. A new sensor for the detection 47 of ammonia, based on zeolites, has been recently proposed 48 although the comparison with conventional measurements is still 49 unclear [21].…”

“…Nowadays, different TP techniques are available and commonly 14 used such as: Temperature Programmed Reduction (TPR), Tem- 15 perature Programmed Oxidation (TPO), Temperature Programmed 16 Sulphidation (TPS), Temperature Programmed Desorption (TPD) 17 and Temperature Programmed Surface Reaction (TPSR). 18 Ammonia Temperature Programmed Desorption (NH 3 -TPD) is 19 one of the most commonly methods used for measuring the 20 surface acidity [2,3,[5][6][7][8]. It is widely applied both for its simplicity 21 and the reduced investment cost.…”

“…In a conventional H 2 -TPR experiment, the 60 catalyst is put in a tubular reactor and fed with a reducing mixture 61 while the temperature is increased according to a program with a 62 ramping rate in the range (5-20 K/min) [1,22,24] with different 63 hydrogen concentrations and different total flow-rates. This 64 technique is quite well-known and commonly applied through 65 the use of different detectors such as TCD [20] and TCD + FID [24]; in 66 some cases, other techniques like monitoring weight variation 67 through TGA-DTA method [25] or less recently detecting pressure 68 change in the reacting gas [22] water production were also carried out as introduced for NH 3 -TPD. Brønsted sites of the P-OH type form [43,44].…”