Study On The Effect Of Modified Zeolite Catalytic Pyrolysis Of Biomass

Rapidly growing energy demands,steadily depleting fossil fuel reserves accompanied by ever-increasing environmental concern shave made unequivocally crucial to seek sustainable and eco-friendly energy resources.Biomass is considered as a potential alternative energy source because of its preparation of bio-oil and versatile chemicals by catalytic pyrolysis,therefore it receives wide spread attention.XRD and BET were used to characterize HZSM-5 molecular sieve supported by Ni/Mo elements.The effect of lignin pyrolysis under 550°C was studied by using pyrolysis chromatography mass spectrometry?Py-GC/MS?with different metal loadings?3%,6%?and composite metal.The yield of phenols and ketones increased during pyrolysis of lignin and the yield of acids and aldehydes products decreased over Ni/Mo modified HZSM-5.The highest selectivity of phenols and the lowest selectivity of acids were produced with adding6%Ni.Furthermore,the addition of Ni and Mo can promote the formation of alcohols and furans.Based on the above research,different nickel salt precursors?Ni SO₄,Ni?CH3COO?₂,Ni Cl₂and Ni?NO₃?₂?were used to take the preparation of modified molecular sieves and they were characterized by XRD,BET and NH₃-TPD.The effect of biomass model compound?cellulose:lignin=2:1?pyrolysis under 500°C was analyzed by using fixed bed and gas chromatography mass spectrometry?GC/MS?.The addition of Ni can promote the transformation of carbonyls,carboxyls and methoxys in catalytic pyrolysis reaction.The pyrolysis of biomass model compound over Ni modified HZSM-5 produced less ketones,phenols and acids products,the yield of phenols and esters increased different degrees,while aldehydes did not change significantly.Meanwhile,the cyclic products were transformed into the chain products,C9 long-chain substances were broken into C5-C8 short-chain substances.The catalytic effect is the most significant with HZSM-5 modified by Ni?NO₃?₂and Ni?CH₃COO?₂,the effect of SO₄^2-is more obvious for the side chain of the benzene ring,while the catalytic performance of Ni-Cl/HZSM-5 has no significant improvement.XRD,XRF,BET and NH₃-TPD were used to characterize HZSM-5 molecular sieve supported by different alkali concentration?0.1,0.2 mol/L?,different species?Na OH,Na₂CO₃?and mixed with organic base solution?CTAB,TPAOH?.The effect of biomass model compound 500°C was studied by Py-GC/MS.Low concentration of Na OH/Na₂CO₃is conducive to the formation of small molecules of ketones,phenols and esters,it can also promote the yield of C5 products to increase bio-oil yield.High concentration of Na OH/Na₂CO₃is more conducive to remove carbonyl and hydroxyl to make the improvement of catalytic performance of HZSM-5,and thus C1-C4 products were increased by the behavior of cyclic products transform into the chain products.The addition of TPAOH takes the positive effect on Na OH,which shows that the yield of ketones is minimized and the yield of phenols and aldehydes substances is increased.Furthermore,TPAOH promotes the transformation of C9 to C1-C4 and the high selectivity of chain products,while CTAB promotes the transformation of C9 to C5-C8 and the high selectivity of cycle products...